View source for LSD

{{Short description|Psychedelic drug}}
{{Redirect-distinguish|Lsd|£sd}}
{{Other uses|LSD (disambiguation)|Lysergic acid diethylamide (disambiguation)}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{Use mdy dates|date=May 2016}}
{{Infobox drug
| Watchedfields = changed
| verifiedrevid = 629704081
| drug_name = Lysergic acid diethylamide
| INN = Lysergide
| image = LSD skeletal formula.svg
| image_class = skin-invert-image
| width = 150px
| caption = [[Skeletal formula]]  of LSD
| image2 = LSD-from-xtal-and-Spartan-PM3-3D-balls-web.png
| image_class2 = bg-transparent
| width2 = 175px
| caption2 = [[Ball-and-stick model|3D stick model]] of LSD 

<!-- Clinical data -->
| tradename = Delysid
| pronounce = {{IPA|/daɪ eθəl ˈæmaɪd/}}, {{IPA|/æmɪd/}}, or {{IPA|/eɪmaɪd/}}<ref>{{cite encyclopedia |url=http://www.collinsdictionary.com/dictionary/english/amide |title=Definition of "amide" |dictionary=Collins English Dictionary |access-date=January 31, 2015 |url-status=live |archive-url=https://web.archive.org/web/20150402115318/http://www.collinsdictionary.com/dictionary/english/amide |archive-date=April 2, 2015}}</ref><ref>{{cite web |url=https://www.ahdictionary.com/word/search.html?q=amide |title=American Heritage Dictionary Entry: amide |publisher=Ahdictionary.com |access-date=January 31, 2015 |archive-url=https://web.archive.org/web/20150402134025/https://www.ahdictionary.com/word/search.html?q=amide |archive-date=April 2, 2015}}</ref><ref>{{cite web |url=http://www.oxforddictionaries.com/us/definition/english/amide |title=amide – definition of amide in English from the ''Oxford Dictionary''|publisher=Oxforddictionaries.com |access-date=January 31, 2015 |archive-url=https://web.archive.org/web/20150402184403/http://www.oxforddictionaries.com/us/definition/english/amide |archive-date=April 2, 2015}}</ref>
| Drugs.com = [https://www.drugs.com/illicit/lsd.html Reference]
| pregnancy_US = C
| MedlinePlus = 
| licence_EU = 
| licence_US = 
| pregnancy_AU = 
| pregnancy_category = C
| addiction_liability = None<ref name="NHM-MDMA"/>
| dependency_liability = Low<ref>{{cite book| vauthors = Halpern JH, Suzuki J, Huertas PE, Passie T | veditors = Price LH, Stolerman IP |title=Encyclopedia of Psychopharmacology A Springer Live Reference|date=June 7, 2014|publisher=Springer-Verlag Berlin Heidelberg|location=Heidelberg, Germany|isbn=978-3-642-27772-6|pages=1–5|quote=Hallucinogen abuse and dependence are known complications resulting from ... LSD and psilocybin. Users do not experience withdrawal symptoms, but the general criteria for substance abuse and dependence otherwise apply. Dependence is estimated in approximately 2 % of recent-onset users |doi=10.1007/978-3-642-27772-6_43-2|chapter=Hallucinogen Abuse and Dependence}}</ref>
| routes_of_administration = [[Oral administration|Oral]]<ref name="TiHKAL" />
| class = [[Serotonin receptor agonist]]; [[Serotonin]] [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]] [[agonist]]; [[Serotonergic psychedelic]]; [[Hallucinogen]]
| ATC_prefix = None
| ATC_suffix = 

<!-- Legal status -->
| legal_AU = Schedule 9
| legal_BR = F2
| legal_CA = Schedule III
| legal_NZ = Class A
| legal_UK = Class A
| legal_UN = P I
| legal_US = Schedule I
| legal_DE = Anlage I
| legal_status = {{ubl
 | SE: Förteckning I
 | [[Illicit drug]]
 }}
 
<!-- Pharmacokinetic data -->
| bioavailability = 80%<ref name="ZhangLinWang2026">{{cite journal | vauthors = Zhang T, Lin C, Wang X | date = 25 May 2026 | title = Overcoming Pharmacokinetic and Peripheral Safety Challenges in Psychedelic Therapies: The Promise of Advanced Drug Delivery Systems | journal = ACS Pharmacology & Translational Science | doi = 10.1021/acsptsci.6c00146 | issn = 2575-9108 }}</ref><ref name="ArikciHolzeMueller2025">{{cite journal | vauthors = Arikci D, Holze F, Mueller L, Vizeli P, Rudin D, Luethi D, Hysek CM, Liechti ME | title = Absolute Oral Bioavailability and Bioequivalence of LSD Base and Tartrate in a Double-Blind, Placebo-Controlled, Crossover Study | journal = Clinical Pharmacology and Therapeutics | volume = 118| issue = 3| pages = 735–743| date = May 2025 | pmid = 40418105 | doi = 10.1002/cpt.3726 | pmc = 12355019 }}</ref><ref name="Holze_2024">{{cite journal | vauthors = Holze F, Mueller L, Vizeli P, Luethi D, Rudin D, Hysek C, Liechti M, Arikci D | title = Oral LSD base and tartrate bioequivalence and absolute bioavailability in healthy participants | journal = Neuroscience Applied | volume = 3 | article-number = 105132 | date = 2024 | doi = 10.1016/j.nsa.2024.105132 | doi-access = free }}</ref>
| protein_bound = Unknown<ref name="PassieHalpernStrichtenoth2008" />
| metabolism = [[Liver]] ([[CYP450]])<ref name="DolderSchmidHaschke2015">{{cite journal |vauthors=Dolder PC, Schmid Y, Haschke M, Rentsch KM, Liechti ME |title=Pharmacokinetics and Concentration-Effect Relationship of Oral LSD in Humans |journal=The International Journal of Neuropsychopharmacology |volume=19 |issue=1 |article-number=pyv072 |date=June 2015 |pmid=26108222 |pmc=4772267 |doi=10.1093/ijnp/pyv072}}</ref>
| metabolites = • [[2-Oxo-3-hydroxy-LSD]]<ref name="DolderSchmidHaschke2015" /><ref name="Dolder2017" /><br />• [[2-Oxo-LSD]]<ref name="Dolder2017" /><br />• {{Abbrlink|LAE|Lysergic acid ethylamide}}<ref name="Dolder2017" /><br />• {{Abbrlink|LEO|Lysergic acid ethyl-2-hydroxyethylamide}}<ref name="Dolder2017" /><br />• [[Nor-LSD]]<ref name="Dolder2017" /><br />• [[13-Hydroxy-LSD]]<ref name="Dolder2017" /><br />• [[14-Hydroxy-LSD]]<ref name="Dolder2017" /><br />• [[Glucuronide]]s<ref name="Dolder2017" />
| onset = [[Oral administration|Oral]]: 0.4–1.0 (range 0.1–1.8) hours<ref name="HolzeSinghLiechti2024" /><ref name="PassieHalpernStrichtenoth2008" /><br />{{Abbrlink|IM|Intramuscular injection}}: 15–20 min<ref name="PassieHalpernStrichtenoth2008" /><br />{{Abbrlink|IV|Intravenous injection}}: 2.5 min<ref name="ArikciHolzeMueller2025" /><br />{{Abbrlink|IT|Intrathecal injection}}: <1 min<ref name="PassieHalpernStrichtenoth2008" /><ref name="Shulgin1980b" />
| duration_of_action = [[Oral administration|Oral]]: 7–12 (range 4–22) hours<ref name="HolzeSinghLiechti2024" /><ref name="PassieHalpernStrichtenoth2008" /><br />{{Abbrlink|IM|Intramuscular injection}}, {{Abbrlink|IV|Intravenous injection}}, {{Abbrlink|IT|Intrathecal injection}}: 8–10 hours<ref name="PassieHalpernStrichtenoth2008" /><ref name="ArikciHolzeMueller2025" />
| elimination_half-life = 3.0–4.3{{nbsp}}hours<ref name="ZhangLinWang2026" /><ref name="DolderSchmidHaschke2015" /><ref name="Muc2016">{{cite journal |vauthors=Mucke HA |title=From Psychiatry to Flower Power and Back Again: The Amazing Story of Lysergic Acid Diethylamide |journal=Assay and Drug Development Technologies |volume=14 |issue=5 |pages=276–281 |date=July 2016 |pmid=27392130 |doi=10.1089/adt.2016.747}}</ref>
| excretion = [[Kidneys]]<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" />

<!-- Identifiers -->
| CAS_number_Ref = {{cascite|correct|CAS}}
| CAS_number = 50-37-3
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 6605
| PubChem = 5761
| IUPHAR_ligand = 17
| DrugBank_Ref = {{drugbankcite|correct|drugbank}}
| DrugBank = DB04829
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 5558
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 8NA5SWF92O
| KEGG_Ref = {{keggcite|correct|kegg}}
| KEGG = C07542
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 263881
| PDB_ligand = 7LD
| synonyms = LSD; LSD-25; LAD; Acid; Lucy; Lysergide; ''d''-LSD; (+)-LSD; (5''R'',8''R'')-LSD; 9,10-Didehydro-''N'',''N''-diethyl-6-methylergoline-8β-carboxamide; ''N'',''N''-Diethyl-''d''-lysergamide; ''d''-Lysergic acid diethylamide; METH-LAD; EA-1729; MM120; MM-120; DT120; DT-120

<!-- Chemical data -->
| IUPAC_name = (6a''R'',9''R'')-''N'',''N''-diethyl-7-methyl-4,6,6a,7,8,9-hexahydroindolo[4,3-''fg'']quinoline-9-carboxamide
| C = 20 | H = 25 | N = 3 | O = 1
| SMILES = CCN(CC)C(=O)[C@H]1CN([C@@H]2Cc3c[nH]c4c3c(ccc4)C2=C1)C
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C20H25N3O/c1-4-23(5-2)20(24)14-9-16-15-7-6-8-17-19(15)13(11-21-17)10-18(16)22(3)12-14/h6-9,11,14,18,21H,4-5,10,12H2,1-3H3/t14-,18-/m1/s1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = VAYOSLLFUXYJDT-RDTXWAMCSA-N

<!-- Physical data -->
| melting_point = 80
| melting_high = 85
| solubility = 67.02<ref>{{cite web|title=Lysergide|url=https://pubchem.ncbi.nlm.nih.gov/compound/5761#section=Solubility|website=pubchem.ncbi.nlm.nih.gov|language=en|access-date=April 12, 2023|archive-date=April 12, 2023|archive-url=https://web.archive.org/web/20230412075752/https://pubchem.ncbi.nlm.nih.gov/compound/5761#section=Solubility|url-status=live}}</ref>
}}

'''Lysergic acid diethylamide''', commonly known as '''LSD''' (from German '''{{lang|de|Lysergsäurediethylamid}}''') and by the nicknames '''acid''' and '''Lucy''', is a [[Semisynthesis|semisynthetic]] [[Hallucinogen|hallucinogenic drug]] derived from [[ergot]], known for its potent psychological effects and [[Serotonin|serotonergic]] activity.<ref>{{Cite web | work = PubChem |title=Lysergide |url=https://pubchem.ncbi.nlm.nih.gov/compound/Lysergide |access-date=2025-05-22 | publisher = U.S. National Library of Medicine |language=en}}</ref>

LSD taken [[oral administration|orally]] has an [[onset of action]] of 0.4 to 1.0{{nbsp}}hours and a [[duration of action|duration]] of 7 to 12{{nbsp}}hours.<ref name="HolzeSinghLiechti2024" /><ref name="PassieHalpernStrichtenoth2008" /> In recreational settings it is commonly administered via tabs of [[Blotting paper|blotter paper]].<ref name="NIH2016">{{cite web |title=What are hallucinogens? |date=January 2016 |url=https://www.drugabuse.gov/publications/drugfacts/hallucinogens |website=National Institute of Drug Abuse |access-date=April 24, 2016 |url-status=live |archive-url=https://web.archive.org/web/20160417180046/https://www.drugabuse.gov/publications/drugfacts/hallucinogens |archive-date=April 17, 2016}}</ref> LSD is extremely [[potency (pharmacology)|potent]], with noticeable effects at doses as low as 20{{nbsp}}[[microgram]]s and is sometimes taken in even smaller amounts for [[psychedelic microdosing|microdosing]].<ref name="Polito2024">{{cite journal | vauthors = Polito V, Liknaitzky P | date = August 2024 | title = Is microdosing a placebo? A rapid review of low-dose LSD and psilocybin research | journal = Journal of Psychopharmacology | volume = 38 | issue = 8 | pages = 701–711 | doi = 10.1177/02698811241254831 | pmc = 11311906 | pmid = 38877715 }}</ref> Despite widespread use, no fatal human [[overdose]]s have been documented. LSD is mainly used [[recreational drug use|recreationally]] or for [[entheogen|spiritual]] purposes.<ref name="EU2018">{{cite web |title=LSD profile (chemistry, effects, other names, synthesis, mode of use, pharmacology, medical use, control status) |url=http://www.emcdda.europa.eu/publications/drug-profiles/lsd |url-status=live |archive-url=https://web.archive.org/web/20210428113546/https://www.emcdda.europa.eu/publications/drug-profiles/lsd |archive-date=April 28, 2021 |access-date=14 July 2018 |website=EMCDDA |language=en}}</ref><ref>{{cite news |vauthors=Gershon L |date=19 July 2016 |title=How LSD Went From Research to Religion |url=https://daily.jstor.org/how-lsd-went-from-research-to-religion/ |access-date=14 July 2018 |work=JSTOR Daily |archive-date=January 28, 2021 |archive-url=https://web.archive.org/web/20210128015545/https://daily.jstor.org/how-lsd-went-from-research-to-religion/ |url-status=live }}</ref> LSD can cause [[mystical experience]]s.<ref>{{cite journal | vauthors = Liechti ME, Dolder PC, Schmid Y | date = May 2017 | title = Alterations of consciousness and mystical-type experiences after acute LSD in humans | journal = Psychopharmacology | volume = 234 | issue = 9–10 | pages = 1499–1510 | doi = 10.1007/s00213-016-4453-0 | pmc = 5420386 | pmid = 27714429 }}</ref><ref>{{cite journal | vauthors = Griffiths RR, Hurwitz ES, Davis AK, Johnson MW, Jesse R | date = 2019-04-23 | title = Survey of subjective "God encounter experiences": Comparisons among naturally occurring experiences and those occasioned by the classic psychedelics psilocybin, LSD, ayahuasca, or DMT | journal = PLOS ONE | volume = 14 | issue = 4 | article-number = e0214377 | doi = 10.1371/journal.pone.0214377 | pmc = 6478303 | pmid = 31013281 | bibcode = 2019PLoSO..1414377G | doi-access = free }}</ref> LSD exerts its effects primarily through high-[[affinity (pharmacology)|affinity]] binding to several [[serotonin receptor]]s, especially the [[serotonin]] [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]], and to a lesser extent [[dopamine receptor|dopamine]] and [[adrenergic receptor]]s. Neuroimaging studies indicate that LSD reduces the efficacy of thalmo-cortical information filtering,<ref name="Preller2018">{{cite journal | vauthors = Preller KH, Burt JB, Ji JL, Schleifer CH, Adkinson BD, Stämpfli P, Seifritz E, Repovs G, Krystal JH, Murray JD, Vollenweider FX, Anticevic A | date = October 2018 | title = Changes in global and thalamic brain connectivity in LSD-induced altered states of consciousness are attributable to the 5-HT2A receptor | journal = eLife | volume = 7 | article-number = e35082 | doi = 10.7554/eLife.35082 | pmc = 6202055 | pmid = 30355445 | doi-access = free }}</ref> decreases [[neural oscillation|oscillatory power]] within the [[default mode network]], and flattens hierarchical organization of large-brain activity.<ref name="Nichols2016">{{cite journal | vauthors = Nichols DE | date = April 2016 | veditors = Barker EL | title = Psychedelics | journal = Pharmacological Reviews | volume = 68 | issue = 2 | pages = 264–355 | doi = 10.1124/pr.115.011478 | pmc = 4813425 | pmid = 26841800 | issn = 0031-6997 }}</ref><ref>{{cite journal | vauthors = Girn M, Roseman L, Bernhardt B, Smallwood J, Carhart-Harris R, Spreng RN | date = 2022 | title = Serotonergic psychedelic drugs LSD and psilocybin reduce the hierarchical differentiation of unimodal and transmodal cortex | journal = NeuroImage | volume = 256 | article-number = 119220 | doi = 10.1016/j.neuroimage.2022.119220 | pmid = 35483649 | biorxiv = 10.1101/2020.05.01.072314 }}</ref> At higher doses, it can induce [[visual hallucination|visual]] and [[auditory hallucination]]s, [[ego death|ego dissolution]], and [[anxiety]].<ref name="LeptourgosFortier-Davy2020">{{cite journal | vauthors = Leptourgos P, Fortier-Davy M, Carhart-Harris R, Corlett PR, Dupuis D, Halberstadt AL, Kometer M, Kozakova E, LarØi F, Noorani TN, Preller KH, Waters F, Zaytseva Y, Jardri R | date = December 2020 | title = Hallucinations Under Psychedelics and in the Schizophrenia Spectrum: An Interdisciplinary and Multiscale Comparison | journal = Schizophrenia Bulletin | volume = 46 | issue = 6 | pages = 1396–1408 | doi = 10.1093/schbul/sbaa117 | pmc = 7707069 | pmid = 32944778 }}</ref><ref name=":3">{{cite journal | vauthors = Holze F, Vizeli P, Ley L, Müller F, Dolder P, Stocker M, Duthaler U, Varghese N, Eckert A, Borgwardt S, Liechti ME | date = February 2021 | title = Acute dose-dependent effects of lysergic acid diethylamide in a double-blind placebo-controlled study in healthy subjects | journal = Neuropsychopharmacology | volume = 46 | issue = 3 | pages = 537–544 | doi = 10.1038/s41386-020-00883-6 | pmc = 8027607 | pmid = 33059356 }}</ref> LSD use can cause adverse psychological effects such as [[paranoia]] and [[delusion]]s and may lead to persistent [[visual disturbance]]s known as [[hallucinogen persisting perception disorder]] (HPPD).

Swiss chemist [[Albert Hofmann]] first synthesized LSD in 1938 and discovered its potent [[psychedelic]] effects in 1943 after accidental ingestion. It became widely studied in the 1950s and 1960s.<ref name="EU2018" /><ref name="NIH2018C">{{cite web |title=Commonly Abused Drugs Charts |url=https://www.drugabuse.gov/drugs-abuse/commonly-abused-drugs-charts#lsd |website=National Institute on Drug Abuse |access-date=14 July 2018 |date=2 July 2018 |url-status=live |archive-url=https://web.archive.org/web/20200301183029/https://www.drugabuse.gov/drugs-abuse/commonly-abused-drugs-charts#lsd |archive-date=March 1, 2020}}</ref> The drug was initially explored for psychiatric use due to its structural similarity to serotonin and safety profile.<ref name="Nichols2018a">{{cite journal |vauthors=Nichols DE |date=October 2018 |title=Dark Classics in Chemical Neuroscience: Lysergic Acid Diethylamide (LSD) |url=https://shaunlacob.com/wp-content/uploads/2020/12/DC-LSD.pdf |journal=ACS Chemical Neuroscience |volume=9 |issue=10 |pages=2331–2343 |doi=10.1021/acschemneuro.8b00043 |pmid=29461039}}</ref> It was used experimentally in [[psychiatry]] for treating [[alcoholism]] and [[schizophrenia]].<ref name="Use of d-lysergic acid diethylamide">{{cite journal |vauthors=Chwelos N, Blewett DB, Smith CM, Hoffer A |title=Use of d-lysergic acid diethylamide in the treatment of alcoholism |journal=Quarterly Journal of Studies on Alcohol |volume=20 |issue=3 |pages=577–590 |date=September 1959 |pmid=13810249 |doi=10.15288/qjsa.1959.20.577}}</ref> By the mid-1960s, LSD became central to the youth [[counterculture]] in places like [[San Francisco]] and [[London]], influencing art, music, and social movements through events like [[Acid Tests]] and figures such as [[Owsley Stanley]] and [[Michael Hollingshead]]. Its psychedelic effects inspired distinct visual art styles and musical innovations, and caused a lasting cultural impact. However, its association with the [[counterculture movement]] of the 1960s led to its classification as a [[Controlled Substances Act#Schedule I|Schedule I]] drug in the [[United States]] in 1970.<ref name="United States Congress House Committee on Interstate and Foreign Commerce Subcommittee on Public Health and Welfare 1968">{{Cite book |author=United States Congress House Committee on Interstate and Foreign Commerce Subcommittee on Public Health and Welfare |url=https://books.google.com/books?id=qbY6xQEACAAJ |title=Increased Controls Over Hallucinogens and Other Dangerous Drugs |date=1968 |publisher=U.S. Government Printing Office |access-date=August 3, 2021|archive-date=July 13, 2020 |archive-url=https://web.archive.org/web/20200713014802/https://books.google.com/books?id=qbY6xQEACAAJ|url-status=live}}</ref> It was also listed as a [[Schedule 1 controlled substance|Schedule I controlled substance]] by the [[United Nations]] in 1971 and remains without approved medical uses.<ref name="EU2018" />

Despite its legal restrictions, LSD remains influential in scientific and cultural contexts. Research on LSD declined due to cultural controversies by the 1960s, but has resurged since 2009. In 2024, the United States [[Food and Drug Administration]] designated LSD (code name MM120 or DT120) as a [[breakthrough therapy]] for [[generalized anxiety disorder]].<ref name="webmd.com">{{Cite web | vauthors = Terry K |date=2024-03-26 |title=FDA Opens the Door to Clinical Use of LSD |url=https://www.webmd.com/mental-health/news/20240326/fda-opens-the-door-clinical-use-lsd |access-date=2024-05-25 |website=WebMD |language=en |archive-date=May 25, 2024 |archive-url=https://web.archive.org/web/20240525075810/https://www.webmd.com/mental-health/news/20240326/fda-opens-the-door-clinical-use-lsd |url-status=live }}</ref> As of 2017, about 10% of people in the United States had used LSD at some point, with 0.7% having used it in the past year.<ref name="NIH2018B">{{cite web|author=National Institute on Drug Abuse|title=Hallucinogens |url=https://www.drugabuse.gov/drugs-abuse/hallucinogens |access-date= January 16, 2026|archive-date=June 3, 2020|archive-url=https://web.archive.org/web/20200603125635/https://www.drugabuse.gov/drugs-abuse/hallucinogens}}</ref> Usage rates have risen, with a 56.4% increase in adult use in the United States from 2015 to 2018.<ref>{{cite journal |vauthors=Yockey RA, Vidourek RA, King KA |title=Trends in LSD use among US adults: 2015–2018 |journal=Drug and Alcohol Dependence |volume=212 |article-number=108071 |date=July 2020 |pmid=32450479 |doi=10.1016/j.drugalcdep.2020.108071 |s2cid=218893155}}</ref>

{{TOC limit}}

==Uses==
===Recreational===
LSD is commonly used as a [[recreational drug]] for its psychedelic effects.<ref>{{cite web|title=DrugFacts: Hallucinogens – LSD, Peyote, Psilocybin, and PCP |url=http://www.drugabuse.gov/publications/drugfacts/hallucinogens-lsd-peyote-psilocybin-pcp|publisher=National Institute on Drug Abuse |access-date=February 17, 2015|date=December 2014|archive-url=https://web.archive.org/web/20150216030833/http://www.drugabuse.gov/publications/drugfacts/hallucinogens-lsd-peyote-psilocybin-pcp |archive-date=February 16, 2015}}</ref>

===Spiritual===
LSD can catalyze intense spiritual experiences and is thus considered an [[entheogen]]. Some users have reported [[out of body]] experiences. In 1966, [[Timothy Leary]] established the [[League for Spiritual Discovery]] with LSD as its [[sacrament]].<ref>{{cite book | vauthors = Fahey DM, Miller JS | veditors = Fahey D, Miller JS | title = Alcohol and Drugs in North America: A Historical Encyclopedia | page = 375 | date = August 27, 2013 | isbn = 978-1-59884-478-8 | publisher = Bloomsbury Academic }}</ref><ref>''[[San Francisco Chronicle]]'' September 20, 1966 Page One</ref> [[Stanislav Grof]] has written that [[religious experience|religious]] and [[mystical experience]]s observed during LSD sessions appear similar to descriptions in [[Sacred Scriptures|sacred scriptures]] of great religions of the world and the texts of ancient [[civilization]]s.<ref name="Grof1979">{{cite book| vauthors=Grof S, Grof JH| author-link1=Stanislav Grof| title=Realms of the Human Unconscious (Observations from LSD Research)| publisher=Souvenir Press (E & A) Ltd| year=1979| location=London| pages=13–14| url=http://www.csp.org/chrestomathy/realms_of3.html| isbn=978-0-285-64882-1| archive-url=https://web.archive.org/web/20071018164416/http://csp.org/chrestomathy/realms_of3.html| archive-date=October 18, 2007| access-date=November 18, 2007}}</ref>

===Medical===
{{See also|Lysergic acid diethylamide#Research}}

LSD currently has no formally approved medical use anywhere in the world.<ref name="Nutt2009">{{cite journal |vauthors=Nutt DJ, King LA, Nichols DE |date=August 2013 |title=Effects of Schedule I drug laws on neuroscience research and treatment innovation |journal=Nature Reviews. Neuroscience |volume=14 |issue=8 |pages=577–585 |doi=10.1038/nrn3530 |pmid=23756634 |s2cid=1956833}}</ref>

In [[Switzerland]], a special authorization program allows limited medical use of substances like LSD for patients with serious, treatment-resistant conditions, with patients treated under physician supervision.<ref>{{cite journal | vauthors = Liechti ME, Gasser P, Aicher HD, Mueller F, Hawrot T, Schmid Y | date = January 2025 | title = Implementing psychedelic-assisted therapy: History and characteristics of the Swiss limited medical use program | journal = Neuroscience Applied | volume = 4 | article-number = 105525 | doi = 10.1016/j.nsa.2025.105525 | pmc = 12341733 | pmid = 40800003 }}</ref>

===Dosing===
{{See also|Psychedelic drug#Dosing}}
[[File:5 LSD blotters.png|thumb|A "five strip" of LSD blotters.]]

LSD is an extraordinarily [[potency (pharmacology)|potent]] substance,<ref name="HolzeSinghLiechti2024" /><ref name="LiechtiHolze2022">{{cite book | vauthors = Liechti ME, Holze F | title = Disruptive Psychopharmacology | chapter = Dosing Psychedelics and MDMA | series = Curr Top Behav Neurosci | volume = 56 | pages = 3–21 | date = 2022 | pmid = 34734392 | doi = 10.1007/7854_2021_270 | isbn = 978-3-031-12183-8 | chapter-url = https://www.researchgate.net/publication/355943062}}</ref><ref name="Nichols2018a" /><ref name="Nichols2018b">{{cite book | vauthors = Nichols DE | title=Behavioral Neurobiology of Psychedelic Drugs | chapter=Chemistry and Structure–Activity Relationships of Psychedelics | series=Current Topics in Behavioral Neurosciences | publisher=Springer Berlin Heidelberg | publication-place=Berlin, Heidelberg | volume=36 | date=2017 | pages=1–43 | isbn=978-3-662-55878-2 | doi=10.1007/7854_2017_475 | pmid=28401524 | chapter-url=https://bibliography.maps.org/resources/download/13937 | archive-url=https://web.archive.org/web/20250323072739/https://bibliography.maps.org/resources/download/13937 | archive-date=March 23, 2025 | quote=Although LSD is the most well-known psychedelic, only a very few structural modifications can be made to its structure, and nearly all of those attenuate its activity by about an order of magnitude. In addition, there is a paucity of structure–activity data for ergolines, principally due to the synthetic difficulty inherent in their chemistry. [...] Although LSD is the most potent psychedelic agent in humans, its affinity and potency at the human 5-HT2A receptor is rather unremarkable compared with much simpler molecules such as DOI. [...] Because of its structural complexity and tedious approaches to its total synthesis, only a few structural modifications of LSD have been reported. [...] Unfortunately, only a few of them have been assessed in human psychopharmacology, most being much less active than LSD itself.}}</ref><ref name="Nichols2001" /> and is one of the most potent psychoactive drugs known.<ref name="Nichols2018a" /><ref name="Nichols2018b" /> This means that it produces its [[pharmacology|pharmacological]] effects at very small doses, with its dose range measured in [[microgram]]s (μg); that is, millionths of a gram.<ref name="HolzeSinghLiechti2024" /><ref name="Nichols2018a" /> Noticeable effects can occur with doses of LSD as low as 20{{nbsp}}μg, which is around 1/200th the mass of a grain of sand.<ref name="HolzeSinghLiechti2024" /><ref name="LiechtiHolze2022" /><ref name="Nichols2018a" /><ref name="EU2018" /> LSD is approximately 200{{nbsp}}times as potent as [[psilocybin]] and 5,000{{nbsp}}times as potent as [[mescaline]], meaning that it produces effects of similar magnitude at 1/200 and 1/5,000 times the respective doses.<ref name="HolzeSinghLiechti2024" /><ref name="LiechtiHolze2022" /><ref name="Hofmann1968">{{cite book | author = [[Albert Hofmann]] | chapter = Psychotomimetic Agents | pages = 169–235 | veditors = Burger A | title = Drugs Affecting the Central Nervous System | volume = 2 | date = 1968 | publisher = M. Dekker | location = New York | oclc = 245452885 | ol = OL13539506M | chapter-url = https://archive.org/details/drugsaffectingce0000edit/page/169/mode/1up | url = https://books.google.com/books?id=o_GMwgEACAAJ | quote = Subsequent experiments on volunteers of the Sandoz research laboratories confirmed the extraordinary activity of lysergic acid diethylamide on the human psyche. These showed that the effective oral dose of LSD in human beings is 0.03—0.05 mg. [...] LSD is by far the most active and most specific psychotomimetic. It is about 5,000—10,000 times more active than mescaline or about 100–200 times more active than psilocybin.}}</ref><ref name="Nichols2001" />

The usual dose range of LSD for psychedelic effects is 20 to 200{{nbsp}}μg.<ref name="HolzeSinghLiechti2024" /><ref name="LiechtiHolze2022" /> The typical intermediate and "good effect" dose for a psychedelic experience is 100{{nbsp}}μg (range 75–150{{nbsp}}μg, while 20 to 50{{nbsp}}μg is a low or "minidose" and 200{{nbsp}}μg is a high or [[ego-dissolution]] dose.)<ref name="HolzeSinghLiechti2024" /><ref name="LiechtiHolze2022" /><ref name="PassieHalpernStrichtenoth2008">{{cite journal |vauthors=Passie T, Halpern JH, Stichtenoth DO, Emrich HM, Hintzen A |date=2008 |title=The pharmacology of lysergic acid diethylamide: a review |url= |journal=CNS Neurosci Ther |volume=14 |issue=4 |pages=295–314 |doi=10.1111/j.1755-5949.2008.00059.x |pmc=6494066 |pmid=19040555}}</ref> A dose range as wide as 10 to 450{{nbsp}}μg has been reported.<ref name="BrimblecombePinder1975">{{cite book | vauthors = Brimblecombe RW, Pinder RM | chapter = Indolealkylamines and Related Compounds | pages = 98–144 | title = Hallucinogenic Agents | date = 1975 | publisher = Wright-Scientechnica | location = Bristol | isbn = 978-0-85608-011-1 | oclc = 2176880 | ol = OL4850660M | url = https://bitnest.netfirms.com/external/Books/978-0-85608-011-1}}</ref><ref name="LuethiLiechti2018">{{cite journal | vauthors = Luethi D, Liechti ME | title = Monoamine Transporter and Receptor Interaction Profiles in Vitro Predict Reported Human Doses of Novel Psychoactive Stimulants and Psychedelics | journal = Int J Neuropsychopharmacol | volume = 21 | issue = 10 | pages = 926–931 | date = October 2018 | pmid = 29850881 | pmc = 6165951 | doi = 10.1093/ijnp/pyy047 }}</ref> LSD may also be used in [[psychedelic microdosing|microdosing]].<ref name="PolitoStevenson2019">{{cite journal |vauthors=Polito V, Stevenson RJ |title=A systematic study of microdosing psychedelics |journal=PLOS ONE |volume=14 |issue=2 |article-number=e0211023 |date=2019-02-06 |pmid=30726251 |pmc=6364961 |doi=10.1371/journal.pone.0211023 |bibcode=2019PLoSO..1411023P |doi-access=free}}</ref> In this context, it may be used at subthreshold or microdoses of less than 10{{nbsp}}μg.<ref name="HolzeSinghLiechti2024" /><ref name="LiechtiHolze2022" />

The extremely high potency of LSD played an essential role in its emergence and popularity during the [[counterculture of the 1960s]] due to the economic feasibility of its manufacture, in contrast to the case of mescaline, which had been known for many decades previously but remained relatively little-known.<ref name="Nichols2001" />

The doses of LSD present in illicit LSD samples have decreased over time. In the mid-1960s, [[Owsley Stanley]], the most important [[black market]] LSD manufacturer in the [[United States]], distributed LSD at a standard concentration of 270{{nbsp}}μg,<ref name="LSD Samples Analysis">{{cite web| vauthors=Hidalgo E| year=2009| title=LSD Samples Analysis| publisher=Erowid| url=http://www.erowid.org/chemicals/lsd/lsd_article3.shtml| access-date=February 8, 2010| url-status=live| archive-url=https://web.archive.org/web/20100213145552/http://www.erowid.org/chemicals/lsd/lsd_article3.shtml| archive-date=February 13, 2010}}</ref> while street samples of the 1970s contained 30 to 300{{nbsp}}μg. By the 1980s, the amount had reduced to between 100 and 125{{nbsp}}μg, dropping more in the 1990s to the 20 to 80{{nbsp}}μg range,<ref name="henderson-glass">{{cite book |vauthors=Henderson LA, Glass WJ |title=LSD: Still with us after all these years |year=1994 |isbn=978-0-7879-4379-0 |publisher=Jossey-Bass |location=San Francisco}}</ref> and even further in the 2000s.<ref name="LSD Samples Analysis" /><ref>{{cite web| author=Fire & Earth Erowid| date=Nov 2003| title=LSD Analysis – Do we know what's in street acid?| url=http://www.erowid.org/chemicals/lsd/lsd_article1.shtml| publisher=Erowid| access-date=February 8, 2010| archive-url=https://web.archive.org/web/20100126215446/http://www.erowid.org/chemicals/lsd/lsd_article1.shtml| archive-date=January 26, 2010| url-status=live}}</ref>

==Effects==
LSD produces a variety of physical, psychological, and sensory effects.<ref name="HolzeSinghLiechti2024" />

===Psychological===
The primary immediate psychological effects of LSD are [[visual hallucination|visual pseudo-hallucinations]] and altered thought, often referred to as "trips". These sensory alterations are considered pseudohallucinations because the subject does not perceive the patterns seen as being located in three-dimensional space outside the body.<ref>{{cite journal | vauthors = El-Mallakh RS, Walker KL | title = Hallucinations, psuedohallucinations, and parahallucinations | journal = Psychiatry | volume = 73 | issue = 1 | pages = 34–42 | date = 2010 | pmid = 20235616 | doi = 10.1521/psyc.2010.73.1.34 }}</ref> LSD is not considered addictive. An "[[afterglow (drug culture)|afterglow]]" effect, characterized by an improved mood or perceived mental state, may persist for days or weeks following ingestion.<ref>{{cite journal |vauthors=Majić T, Schmidt TT, Gallinat J |title=Peak experiences and the afterglow phenomenon: when and how do therapeutic effects of hallucinogens depend on psychedelic experiences? |journal=Journal of Psychopharmacology |volume=29 |issue=3 |pages=241–253 |date=March 2015 |pmid=25670401 |doi=10.1177/0269881114568040 |s2cid=16483172}}</ref> Positive experiences, or "good trips", are described as intensely pleasurable and can include feelings of joy, euphoria, an increased appreciation for life, decreased anxiety, a sense of spiritual enlightenment, and a feeling of interconnectedness with the universe.<ref name="erowid-faq">{{cite web |work=[[Erowid]] |vauthors=Honig D |title=Frequently Asked Questions |url=http://www.erowid.org/chemicals/lsd/lsd_faq.shtml |archive-url=https://web.archive.org/web/20160212232436/https://www.erowid.org/chemicals/lsd/lsd_faq.shtml |archive-date=12 February 2016}}</ref><ref name="PMID6054248">{{cite journal |vauthors=McGlothlin W, Cohen S, McGlothlin MS |title=Long lasting effects of LSD on normals |journal=Archives of General Psychiatry |volume=17 |issue=5 |pages=521–532 |date=November 1967 |pmid=6054248 |doi=10.1001/archpsyc.1967.01730290009002| url=http://www.maps.org/w3pb/new/1967/1967_mcglothlin_4655_1.pdf |archive-date=April 30, 2011 |archive-url=https://web.archive.org/web/20110430020912/http://www.maps.org/w3pb/new/1967/1967_mcglothlin_4655_1.pdf}}</ref>

Negative experiences, commonly known as "[[bad trip]]s", can induce feelings of fear, agitation, anxiety, panic, and paranoia.<ref name="PassieHalpernStrichtenoth2008" /><ref name="kopra_adverse">{{cite journal | vauthors = Kopra EI, Ferris JA, Rucker JJ, McClure B, Young AH, Copeland CS, Winstock AR | title = Adverse experiences resulting in emergency medical treatment seeking following the use of lysergic acid diethylamide (LSD) | journal = Journal of Psychopharmacology | volume = 36 | issue = 8 | pages = 956–964 | date = August 2022 | pmid = 35672900 | pmc = 9353972 | doi = 10.1177/02698811221099650 }}</ref> While the occurrence of a bad trip is unpredictable, factors such as mood, surroundings, sleep, hydration, and social setting, collectively referred to as "[[set and setting]]", can influence the risk and are considered important in minimizing the likelihood of a negative experience.<ref name=MedlinePlus>{{citation |title=Substance use – LSD |vauthors=Rogge T |date=21 May 2014 |access-date=14 July 2016 |publisher=MedlinePlus, U.S. National Library of Medicine |url=https://medlineplus.gov/ency/patientinstructions/000795.htm |url-status=live|archive-url=https://web.archive.org/web/20160728004220/https://medlineplus.gov/ency/patientinstructions/000795.htm|archive-date=July 28, 2016}}</ref><ref name=CESAR>{{citation|title=LSD |author=CESAR |publisher=Center for Substance Abuse Research, University of Maryland |date=29 October 2013 |access-date=14 July 2016 |url=http://www.cesar.umd.edu/cesar/drugs/lsd.asp |archive-url=https://web.archive.org/web/20160715071823/http://www.cesar.umd.edu/cesar/drugs/lsd.asp |archive-date=July 15, 2016}}</ref>

Uniquely among psychedelics, LSD appears to have two temporally and qualitatively distinct phases of psychoactive effects.<ref name="Nichols2016" /><ref name="KuypersNgErritzoe2019">{{cite journal | vauthors = Kuypers KP, Ng L, Erritzoe D, Knudsen GM, Nichols CD, Nichols DE, Pani L, Soula A, Nutt D | title = Microdosing psychedelics: More questions than answers? An overview and suggestions for future research | journal = J Psychopharmacol | volume = 33 | issue = 9 | pages = 1039–1057 | date = September 2019 | pmid = 31303095 | pmc = 6732823 | doi = 10.1177/0269881119857204 | url = }}</ref><ref name="KyzarNicholsGainetdinov2017">{{cite journal | vauthors = Kyzar EJ, Nichols CD, Gainetdinov RR, Nichols DE, Kalueff AV | title = Psychedelic Drugs in Biomedicine | journal = Trends Pharmacol Sci | volume = 38 | issue = 11 | pages = 992–1005 | date = November 2017 | pmid = 28947075 | doi = 10.1016/j.tips.2017.08.003 | url = }}</ref><ref name="Marona-LewickaNicholsNichols2011">{{cite journal | vauthors = Marona-Lewicka D, Nichols CD, Nichols DE | title = An animal model of schizophrenia based on chronic LSD administration: old idea, new results | journal = Neuropharmacology | volume = 61 | issue = 3 | pages = 503–512 | date = September 2011 | pmid = 21352832 | pmc = 3110609 | doi = 10.1016/j.neuropharm.2011.02.006 | url = }}</ref><ref name="Freedman1984">{{cite book | vauthors = [[Daniel X. Freedman|Freedman DX]] | chapter=The Bridge from Human to Animal. Hallucinogens: Neurochemical, Behavioral, and Clinical Perspectives | veditors = Jacobs BL | title=Hallucinogens, Neurochemical, Behavioral, and Clinical Perspectives | publisher=Raven Press | series=Central Nervous System Pharmacology | year=1984 | isbn=978-0-89004-990-7 | chapter-url=https://archive.org/details/lsd-bridge-freedman-hallucinogens-jacobs-1984 | url=https://books.google.com/books?id=EdpsAAAAMAAJ | pages=203–226}}</ref> These include an initial psychedelic phase associated with [[serotonin]] [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]] [[agonism]] and a subsequent [[paranoia]]- and [[psychosis]]-like phase associated with [[dopamine]] [[D2-like receptor|D<sub>2</sub>-like receptor]] agonism.<ref name="Nichols2016" /><ref name="KyzarNicholsGainetdinov2017" /><ref name="Marona-LewickaNicholsNichols2011" /><ref name="Freedman1984" /> The first phase is described as a "psychedelic experience", with "meaningfulness and portentousness" as the primary effects, while the latter phase is "clearly a paranoid state", including feeling "at the least self-centered, and usually suspicious, with ideas of reference or even paranoid convictions".<ref name="Nichols2016" /><ref name="Marona-LewickaNicholsNichols2011" /><ref name="Freedman1984" /> The second phase typically develops about 4 to 6{{nbsp}}hours after administration but at times up to 10{{nbsp}}hours after administration.<ref name="Nichols2016" /><ref name="Marona-LewickaNicholsNichols2011" /><ref name="Freedman1984" /> Parallels have been drawn between this phase and [[amphetamine psychosis]].<ref name="Marona-LewickaNicholsNichols2011" /><ref name="Freedman1984" /> There is no indication that similar effects occur with other psychedelics like [[substituted phenethylamine|phenethylamine]]s and simple [[substituted tryptamine|tryptamine]]s, which lack [[dopamine receptor agonism]].<ref name="Marona-LewickaNicholsNichols2011" /> The preceding findings have been described by researchers like [[Daniel X. Freedman]] and [[David E. Nichols]].<ref name="Nichols2016" /><ref name="Marona-LewickaNicholsNichols2011" /><ref name="Freedman1984" />

===Sensory===
LSD induces an animated sensory experience affecting senses, emotions, memories, time, and awareness. The effects range from subtle perceptual changes to profound [[cognitive shift]]s. Alterations in auditory and visual perception are common.<ref name="linton-langs"/><ref>{{cite journal |vauthors=Katz MM, Waskow IE, Olsson J |title=Characterizing the psychological state produced by LSD |journal=Journal of Abnormal Psychology |volume=73 |issue=1 |pages=1–14 |date=February 1968 |pmid=5639999 |doi=10.1037/h0020114 |citeseerx=10.1.1.409.4030}}</ref>

Users may experience enhanced visual phenomena, such as vibrant colors, objects appearing to morph, ripple, or move, and geometric patterns on various surfaces. Changes in the perception of food's texture and taste are also noted, sometimes leading to aversion towards certain foods.<ref name="linton-langs">{{cite journal |journal=Archives of General Psychiatry |title=Subjective Reactions to Lysergic Acid Diethylamide (LSD-25) |date=May 1962 |volume=6 |issue=5 |pages=352–368 |doi=10.1001/archpsyc.1962.01710230020003 |vauthors=Linton HR, Langs RJ}}</ref><ref>{{cite journal |vauthors=Parker LA |title=LSD produces place preference and flavor avoidance but does not produce flavor aversion in rats |journal=Behavioral Neuroscience |volume=110 |issue=3 | pages=503–508 |date=June 1996 |pmid=8888996 |doi=10.1037/0735-7044.110.3.503}}</ref>

There are reports of inanimate objects appearing animated, with static objects seeming to move in additional spatial dimensions.<ref>{{cite journal |vauthors=Oster G |title=Moiré patterns and visual hallucinations |journal=Psychedelic Review |date=1966 |volume=7 |pages=33–40 |url= https://maps.org/research-archive/psychedelicreview/n07/n07033osl.pdf |url-status=live |archive-date=19 April 2017 |archive-url=https://web.archive.org/web/20170419154504/http://www.maps.org/research-archive/psychedelicreview/n07/n07033osl.pdf}}</ref> The auditory effects of LSD may include [[echo]]-like distortions of sounds, and an intensified experience of music. Basic visual effects often resemble [[phosphenes]] and can be influenced by concentration, thoughts, emotions, or music.<ref>{{cite journal |vauthors=Kaelen M, Roseman L, Kahan J, Santos-Ribeiro A, Orban C, Lorenz R, Barrett FS, Bolstridge M, Williams T, Williams L, Wall MB, Feilding A, Muthukumaraswamy S, Nutt DJ, Carhart-Harris R |date=July 2016 |title=LSD modulates music-induced imagery via changes in parahippocampal connectivity |journal=European Neuropsychopharmacology |volume=26 |issue=7 |pages=1099–1109 |pmid=27084302 |doi=10.1016/j.euroneuro.2016.03.018 |s2cid=24037275}}</ref> Higher doses can lead to more intense sensory perception alterations, including synesthesia, perception of additional dimensions, and temporary [[Dissociation (psychology)|dissociation]].

===Physical===
[[File:Possible physical effects of lysergic acid diethylamide (LSD).svg|thumb|upright=1|Some symptoms reported for LSD.<ref name=NIDA>{{cite web |date=June 2009 |title=Hallucinogens – LSD, Peyote, Psilocybin, and PCP |publisher=The National Institute on Drug Abuse (NIDA) |url=http://www.nida.nih.gov/infofacts/hallucinogens.html |work=NIDA InfoFacts|archive-date=21 November 2009|archive-url=https://web.archive.org/web/20091121195932/http://www.nida.nih.gov/infofacts/hallucinogens.html}}</ref><ref name=Schiff>{{cite journal |vauthors=Schiff PL |title=Ergot and its alkaloids |journal=American Journal of Pharmaceutical Education |volume=70 |issue=5 |page=98 |date=October 2006 |pmid=17149427 |pmc=1637017 |doi=10.5688/aj700598 |doi-broken-date=March 30, 2026 }}</ref>]]
[[File:Mydriasis due to LSD usage.jpg|alt=Patient with Mydriasis due to usage of LSD|thumb|upright=1|left|Patient with [[mydriasis]] (pupil dilation) due to usage of LSD.]]

LSD can induce physical effects such as [[Mydriasis|pupil dilation]], decreased [[appetite]], increased [[sweating]], and [[wakefulness]]. The physical reactions to LSD vary greatly, and some may be a result of its psychological effects. Commonly observed symptoms include increased [[body temperature]], [[blood sugar]], and [[heart rate]], as well as [[goose bumps]], [[Bruxism|jaw clenching]], [[dry mouth]], and [[hyperreflexia]]. In cases of adverse reactions, users may experience [[numbness]], [[weakness]], [[nausea]], and [[tremor]]s.<ref name="EU2018" />

===Onset and duration===
The psychoactive effects of LSD last on average between 7 and 11{{nbsp}}hours, with a possible range of 4 to 22{{nbsp}}hours.<ref name="HolzeSinghLiechti2024" /> Higher doses tend to lead to a longer duration of action.<ref name="HolzeSinghLiechti2024" /> The [[onset of action]] when administered orally is 0.4 to 1.0{{nbsp}}hours on average, with a possible range of 0.1 to 1.8{{nbsp}}hours.<ref name="HolzeSinghLiechti2024" /> The time to peak effects given orally is 2.2 to 2.8{{nbsp}}hours on average, with a range of 1.3 to 6.5{{nbsp}}hours.<ref name="HolzeSinghLiechti2024" />

The duration of LSD can be shortened through the use of [[trip killer|trip killers or shorteners]] like [[ketanserin]].<ref name="HalmanKongSarris2024" /><ref name="BeckerKlaiberHolze2023">{{Cite journal |vauthors=Becker AM, Klaiber A, Holze F, Istampoulouoglou I, Duthaler U, Varghese N, Eckert A, Liechti ME |date=February 2023 |title=Ketanserin Reverses the Acute Response to LSD in a Randomized, Double-Blind, Placebo-Controlled, Crossover Study in Healthy Participants |journal=Int J Neuropsychopharmacol |volume=26 |issue=2 |pages=97–106 |doi=10.1093/ijnp/pyac075 |pmid=36342343 |pmc=9926053}}</ref> In a [[clinical trial]], ketanserin given 1{{nbsp}}hour after LSD shortened its duration from 8.5{{nbsp}}hours to 3.5{{nbsp}}hours or by about 60%.<ref name="HalmanKongSarris2024" /><ref name="BeckerKlaiberHolze2023" />

==Adverse effects==
[[File:HarmCausedByDrugsTable.svg|thumb|upright=1.35|class=skin-invert-image|Table from the 2010 ISCD study ranking various drugs (legal and illegal) based on statements by drug-harm experts. LSD was found to be the 18th most dangerous out of 20 considered.<ref name="Nutt_2010">{{cite journal | vauthors = Nutt DJ, King LA, Phillips LD | title = Drug harms in the UK: a multicriteria decision analysis | journal = Lancet | volume = 376 | issue = 9752 | pages = 1558–1565 | date = November 2010 | pmid = 21036393 | doi = 10.1016/S0140-6736(10)61462-6 | bibcode = 2010Lanc..376.1558N | s2cid = 5667719 | citeseerx = 10.1.1.690.1283 }}</ref>]]

[[File:Rational harm assessment of drugs radar plot.svg|thumb|upright=1.35|class=skin-invert-image|Addiction experts in psychiatry, chemistry, pharmacology, forensic science, epidemiology, and the police and legal services engaged in [[Delphi method|delphic analysis]] regarding 20 popular recreational drugs. LSD was ranked 14th in dependence, 15th in physical harm, and 13th in social harm.<ref>{{cite journal |vauthors=Nutt D, King LA, Saulsbury W, Blakemore C |title=Development of a rational scale to assess the harm of drugs of potential misuse |journal=Lancet |volume=369 |issue=9566 |pages=1047–53 |date=March 2007 |pmid=17382831 |doi=10.1016/s0140-6736(07)60464-4 |bibcode=2007Lanc..369.1047N |s2cid=5903121}}</ref>]]

LSD, a classical psychedelic, is deemed physiologically safe at standard doses (50–200 μg), and its primary risks lie in psychological effects rather than physiological harm.<ref name="Nichols2004">{{cite journal |vauthors=Nichols DE |date=February 2004 |title=Hallucinogens |journal=Pharmacology & Therapeutics |volume=101 |issue=2 |pages=131–181 |doi=10.1016/j.pharmthera.2003.11.002 |issn=1879-016X |pmid=14761703}}</ref><ref name="NicholsGrob2021">{{cite journal |journal=Forensic Science International |vauthors=Nichols DE, Grob CS |doi=10.1016/j.forsciint.2018.01.006 |title=Is LSD Toxic? |volume=284 |pages=141–145 |date=March 2018 |pmid=29408722}}</ref> A 2010 study by [[David Nutt]] ranked LSD as significantly less harmful than [[alcohol (drug)|alcohol]], placing it near the bottom of a list assessing the harm of 20 drugs.<ref name="pmid21036393">{{cite journal |vauthors=Nutt DJ, King LA, Phillips LD |title=Drug harms in the UK: a multicriteria decision analysis |journal=Lancet |volume=376 |issue=9752 |pages=1558–65 |date=November 2010 |pmid=21036393 |doi=10.1016/s0140-6736(10)61462-6 |bibcode=2010Lanc..376.1558N |s2cid=5667719 |citeseerx=10.1.1.690.1283}}</ref>

===Psychological effects===
====Mental disorders====
LSD can induce [[panic attacks]] or extreme anxiety, colloquially termed a "[[bad trip]]". Despite lower rates of depression and substance abuse found in psychedelic drug users compared to controls, LSD presents heightened risks for individuals with severe mental illnesses like [[schizophrenia]].<ref>{{cite journal |vauthors=Krebs TS, Johansen PØ |title=Psychedelics and mental health: a population study |journal=PLOS ONE |volume=8 |issue=8 |article-number=e63972 |date=2013-08-19 |pmid=23976938 |pmc=3747247 |doi=10.1371/journal.pone.0063972 |bibcode=2013PLoSO...863972K |veditors=Lu L |doi-access=free}}</ref><ref name="Murray">{{citation |title=What can we learn about schizophrenia from studying the human model, drug-induced psychosis?|vauthors=Murray RM, Paparelli A, Morrison PD, Marconi A, Di Forti M |journal=American Journal of Medical Genetics Part B |volume=162 |issue=7 |series=Special Issue: Identifying the Origins of Mental Illness: A Festschrift in Honor of Ming T. Tsuang |pages=661–670 |date=October 2013 |pmid=24132898 |s2cid=205326399 |doi=10.1002/ajmg.b.32177 |doi-access=free}}</ref> These hallucinogens can catalyze psychiatric disorders in predisposed individuals, although they do not tend to induce illness in emotionally healthy people.<ref name="Nichols2004" />

====Suggestibility====
While research from the 1960s indicated increased suggestibility under the influence of LSD among both mentally ill and healthy individuals, recent documents suggest that the CIA and Department of Defense have discontinued research into LSD as a means of mind control.<ref>{{cite web |url= http://www.gulfweb.org/bigdoc/rockrep.cfm#hallucinogens |title=Is Military Research Hazardous to Veterans Health? Lessons Spanning Half A Century, part F. HALLUCINOGENS |publisher=103rd Congress, 2nd Session-S. Prt. 103-97; Staff Report prepared for the committee on veterans' affairs |date=December 8, 1994 |vauthors=Rockefeller IV JD |location=West Virginia |archive-url=https://web.archive.org/web/20060813164326/http://gulfweb.org/bigdoc/rockrep.cfm#hallucinogens |archive-date=August 13, 2006 |access-date=December 13, 2018}}</ref><ref>{{cite journal |vauthors=Middlefell R |title=The effects of LSD on body sway suggestibility in a group of hospital patients |journal=The British Journal of Psychiatry |volume=113 |issue=496 |pages=277–280 |date=March 1967 |pmid=6029626 |doi=10.1192/bjp.113.496.277 |s2cid=19439549 |url= http://www.lycaeum.org/research/researchpdfs/1489.pdf |archive-url=https://web.archive.org/web/20110430033215/http://www.lycaeum.org/research/researchpdfs/1489.pdf |archive-date=2011-04-30}}</ref><ref>{{cite journal |vauthors=Sjoberg BM, Hollister LE |title=The effects of psychotomimetic drugs on primary suggestibility |journal=Psychopharmacologia |volume=8 |issue=4 |pages=251–262 |date=November 1965 |pmid=5885648 |doi=10.1007/BF00407857 |s2cid=15249061}}</ref>{{Primary source inline|date=June 2023}}

====Flashbacks====
{{See also|Urban legends about drugs#"Permatripping" and retention of LSD in spinal fluid}}

[[Flashback (psychology)|Flashbacks]] are psychological episodes where individuals re-experience some of LSD's subjective effects after the drug has worn off, persisting for days or months post-[[hallucinogen]] use.<ref name="Halpern2003">{{cite journal |vauthors=Halpern JH, Pope HG |title=Hallucinogen persisting perception disorder: what do we know after 50 years? |journal=Drug and Alcohol Dependence |volume=69 |issue=2 |pages=109–19 |date=March 2003 |pmid=12609692 |doi=10.1016/S0376-8716(02)00306-X}}</ref><ref>{{cite journal |vauthors=Müller F, Kraus E, Holze F, Becker A, Ley L, Schmid Y, Vizeli P, Liechti ME, Borgwardt S |title=Flashback phenomena after administration of LSD and psilocybin in controlled studies with healthy participants |journal=Psychopharmacology |date=January 2022 |volume=239 |issue=6 |pages=1933–1943 |pmid=35076721 |doi=10.1007/s00213-022-06066-z |pmc=9166883 |s2cid=246276633}}</ref> These experiences are associated with [[hallucinogen persisting perception disorder]] (HPPD), where flashbacks occur intermittently or chronically, causing distress or functional impairment.<ref name="Halpern2018">{{cite book |title=A Review of Hallucinogen Persisting Perception Disorder (HPPD) and an Exploratory Study of Subjects Claiming Symptoms of HPPD. |vauthors=Halpern JH, Lerner AG, Passie T |date=2018 |isbn=978-3-662-55878-2 |series=Current Topics in Behavioral Neurosciences |volume=36 |pages=333–360 |doi=10.1007/7854_2016_457 |pmid=27822679}}</ref>

The etiology of flashbacks is varied. Some cases are attributed to [[somatic symptom disorder]], where individuals fixate on normal [[Somatic nervous system|somatic]] experiences previously unnoticed before drug consumption.<ref>{{cite journal |vauthors=Johansen PØ, Krebs TS |title=Psychedelics not linked to mental health problems or suicidal behavior: a population study |journal=Journal of Psychopharmacology |volume=29 |issue=3 |pages=270–279 |date=March 2015 |doi=10.1177/0269881114568039 |pmid=25744618 |s2cid=2025731}}</ref> Other instances are linked to associative reactions to contextual cues, similar to responses observed in individuals with past trauma or emotional experiences.<ref>{{cite book |vauthors=Holland D, Passie T |isbn=978-3-86135-207-5 |language=de |year=2011 |title=Flashback-Phänomene als Nachwirkung von Halluzinogeneinnahme |volume=2 |series=Bewusstsein – Kognition – Erleben |publisher=VWB Report |url=http://www.vwb-verlag.com/Katalog/m207.html |access-date=June 9, 2023 |archive-date=June 9, 2023 |archive-url=https://web.archive.org/web/20230609015208/http://www.vwb-verlag.com/Katalog/m207.html |url-status=live }}</ref> The risk factors for flashbacks remain unclear, but pre-existing psychopathologies may be significant contributors.<ref>{{cite journal |vauthors=Abraham HD, Duffy FH |date=October 1996 |title=Stable quantitative EEG difference in post-LSD visual disorder by split-half analysis: evidence for disinhibition |journal=Psychiatry Research |volume=67 |issue=3 |pages=173–87 |pmid=8912957 |doi=10.1016/0925-4927(96)02833-8 |s2cid=7587687}}</ref>

Estimating the prevalence of HPPD is challenging. It is considered rare, with occurrences ranging from 1 in 20 users experiencing the transient and less severe type 1 HPPD, to 1 in 50,000 for the more concerning type 2 HPPD.<ref name="Halpern2018"/> Contrary to [[Urban legends about drugs#"Permatripping" and retention of LSD in spinal fluid|internet rumors]], LSD is not stored long-term in the [[spinal cord]] or other parts of the body. Pharmacological evidence indicates LSD has a half-life of 175 minutes and is metabolized into water-soluble compounds like 2-oxo-3-hydroxy-LSD, eliminated through urine without evidence of long-term storage.<ref name="PassieHalpernStrichtenoth2008" /> Clinical evidence also suggests that chronic use of [[SSRI]]s can potentiate LSD-induced flashbacks, even months after stopping LSD use.<ref name="drug-interaction">{{cite book |title=Psychedelics as Psychiatric Medications |publisher=[[Oxford University Press]] |isbn=978-0-19-267852-2 |url=https://books.google.com/books?id=7lazEAAAQBAJ |date=7 March 2023 |vauthors=Nutt DJ, Castle D |chapter=Drug-interaction with psychotropic drugs |access-date=May 21, 2023 |archive-date=May 21, 2023 |archive-url=https://web.archive.org/web/20230521000115/https://books.google.com/books?id=7lazEAAAQBAJ |url-status=live }}</ref>{{rp|145}}

===Tolerance===
LSD shows significant [[tachyphylaxis]], with tolerance developing 24 hours after administration. The progression of tolerance at intervals shorter than 24 hours remains largely unknown.<ref>{{cite book |vauthors=Buchborn T, Grecksch G, Dieterich D, Hollt V |title=Neuropathology of Drug Addictions and Substance Misuse |doi=10.1016/B978-0-12-800212-4.00079-0 |chapter=Chapter 79 - Tolerance to Lysergic Acid Diethylamide: Overview, Correlates, and Clinical Implications |isbn=978-0-12-800212-4 |publisher=[[Academic Press]] |pages=848–849 |volume=2 |year=2016}}</ref> Tolerance typically resets to baseline after 3–4 days of abstinence.<ref name="pmid28701958">{{cite journal |title=A Single Dose of LSD Does Not Alter Gene Expression of the Serotonin 2A Receptor Gene (HTR2A) or Early Growth Response Genes (EGR1-3) in Healthy Subjects |vauthors=Dolder DS, Grünblatt E, Müller F, Borgwardt SJ, Liechti ME |date=28 June 2017 |doi=10.3389/fphar.2017.00423 |journal=Frontiers in Neuroscience |volume=8 |article-number=423 |pmid=28701958 |pmc=5487530 |doi-access=free}}</ref><ref>{{cite journal |journal=Pain Practice |page=455 |volume=23 |issue=4 |issn=1533-2500 |doi=10.1111/papr.13203 |doi-access=free |vauthors=Kooijman NI, Willegers T, Reuser A, Mulleners WM, Kramers C, ((Vissers KCP)), ((van der Wal SEI)) |date=4 January 2023 |pmid=36597700 |title=Are psychedelics the answer to chronic pain: A review of current literature| s2cid=255470638 |hdl=2066/291903 |hdl-access=free}}</ref> Significant cross-tolerance occurs between LSD, [[mescaline]] and [[psilocybin]].<ref name="isbell_mescaline">{{cite journal |vauthors=Wolbach AB, Isbell H, Miner EJ |date=March 1962 |title=Cross tolerance between mescaline and LSD-25, with a comparison of the mescaline and LSD reactions |journal=Psychopharmacologia |volume=3 |pages=1–14 |pmid=14007904 |doi=10.1007/BF00413101 |s2cid=23803624 |url=http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=2032&DocPartID=1893 |access-date=December 1, 2007 |archive-date=April 19, 2014 |archive-url=https://web.archive.org/web/20140419141528/http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=2032&DocPartID=1893}}</ref><ref name="isbell_psilocybin">{{cite journal |vauthors=Isbell H, Wolbach AB, Wikler A, Miner EJ |title=Cross tolerance between LSD and psilocybin |journal=Psychopharmacologia |volume=2 |issue=3 |pages=147–159 |year=1961 |doi=10.1007/BF00407974 |url=http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=1979&DocPartID=1843 |access-date=December 1, 2007 |pmid=13717955 |s2cid=7746880 |archive-date=March 15, 2016 |archive-url=https://web.archive.org/web/20160315102433/https://www.erowid.org/references/refs_view.php?a=showdocpartframe&c=ref&docpartid=1843&id=1979 |url-status=live }}</ref> A slight cross-tolerance to [[DMT]] is observed in humans highly tolerant to LSD.<ref>{{cite journal |vauthors=Rosenberg D, Isbell H, Miner E, Logan C |doi=10.1007/BF00413244 |date=7 August 1963 |title=The effect of N,N-dimethyltryptamine in human subjects tolerant to lysergic acid diethylamide |journal=Psychopharmacologia |volume=5 |issue=3 |pages=223–224 |pmid=14138757 |s2cid=32950588}}</ref> Tolerance to LSD also builds up with consistent use,<ref name="springer">{{cite journal |vauthors=Jonas S, Downer JD |title=Gross behavioural changes in monkeys following administration of LSD-25, and development of tolerance to LSD-25 |journal=Psychopharmacologia |volume=6 |issue=4 |pages=303–386 |date=October 1964 |pmid=4953438 |doi=10.1007/BF00413161 |s2cid=11768927}}</ref> and is believed to result from serotonin 5-HT<sub>2A</sub> [[Downregulation and upregulation#Downregulation and upregulation of receptors|receptor downregulation]].<ref name="pmid28701958" /> Researchers believe that tolerance returns to baseline after two weeks of not using psychedelics.<ref name=lsdtol>{{cite journal |vauthors=Schlemmer RF, Nawara C, Heinze WJ, Davis JM, Advokat C |title=Influence of environmental context on tolerance to LSD-induced behavior in primates |journal=Biological Psychiatry |volume=21 |issue=3 |pages=314–317 |date=March 1986 |pmid=3947713 |doi=10.1016/0006-3223(86)90053-3 |s2cid=35508993}}</ref>

===Addiction and dependence liability===
LSD is widely considered to be non-addictive, despite its potential for [[Substance abuse|abuse]].<ref name="NHM-MDMA">{{cite book |vauthors=Malenka RC, Nestler EJ, Hyman SE |veditors=Sydor A, Brown RY |title=Molecular Neuropharmacology: A Foundation for Clinical Neuroscience |year=2009 |publisher=McGraw-Hill Medical |location=New York |isbn=978-0-07-148127-4 |page=375 |edition=2nd |chapter=Chapter 15: Reinforcement and Addictive Disorders |quote=Several other classes of drugs are categorized as drugs of abuse but rarely produce compulsive use. These include psychedelic agents, such as lysergic acid diethylamide (LSD) |url=https://books.google.com/books?id=PjgfBQAAQBAJ |access-date=June 12, 2023 |archive-date=August 28, 2023 |archive-url=https://web.archive.org/web/20230828020503/https://books.google.com/books?id=PjgfBQAAQBAJ |url-status=live }}</ref><ref name="Nichols2004" /><ref name="Lus2006">{{cite journal |vauthors=Lüscher C, Ungless MA |title=The mechanistic classification of addictive drugs |journal=PLOS Medicine |volume=3 |issue=11 |article-number=e437 |date=November 2006 |pmid=17105338 |pmc=1635740 |doi=10.1371/journal.pmed.0030437 |doi-access=free}}</ref><ref name="clinicalLSD"/> Attempts to train laboratory animals to [[self-administer]] LSD have been largely unsuccessful.<ref name="Nichols2004" /> Although tolerance to LSD builds up rapidly, a [[withdrawal syndrome]] does not appear, suggesting that a potential syndrome does not necessarily relate to the possibility of acquiring rapid tolerance to a substance.<ref>{{cite journal  |vauthors=Balestrieri A, Fontanari D |date=September 1959 |doi=10.1001/archpsyc.1959.03590030063008 |pages=279–282 |pmid=13796178 |title=Acquired and crossed tolerance to mescaline, LSD-25, and BOL-148|journal=Archives of General Psychiatry | volume=1 |issue=3}}</ref> A report examining [[substance use disorder]] for [[Diagnostic and Statistical Manual of Mental Disorders|DSM-IV]] noted that almost no hallucinogens produced dependence, unlike psychoactive drugs of other classes such as [[stimulants]] and [[depressant]]s.<ref name="pmid29366418">{{cite journal |journal=Current Neuropharmacology |volume=17 |issue=2 |pages=1–15 |title=Ayahuasca: Psychological and Physiologic Effects, Pharmacology and Potential Uses in Addiction and Mental Illness |doi=10.2174/1570159X16666180125095902 |doi-access=free |issn=1875-6190 |vauthors=Hamill J, Hallak J, Dursun SD, Baker G |year=2019 |pmid=29366418| pmc=6343205}}</ref><ref>{{cite journal |journal=Addiction |publisher=Society for the Study of Addiction |vauthors=Morgenstern J, Langenbucher J, Labouvie E |date=September 1994 |title=The generalizability of the dependence syndrome across substances: an examination of some properties of the proposed DSM-IV dependence criteria |volume=89 |issue=9 |pages=1105–1113 |doi=10.1111/j.1360-0443.1994.tb02787.x |pmid=7987187}}</ref>

===Cancer and pregnancy===
The [[Mutagenesis|mutagenic]] potential of LSD is unclear. Overall, the evidence points to limited or no effect at commonly used doses.<ref>{{cite journal |vauthors=Li JH, Lin LF |title=Genetic toxicology of abused drugs: a brief review |journal=Mutagenesis |volume=13 |issue=6 |pages=557–65 |date=November 1998 |pmid=9862186 |doi=10.1093/mutage/13.6.557 |doi-access=free}}</ref> Studies showed no evidence of [[teratogenic]] or mutagenic effects.<ref name="PassieHalpernStrichtenoth2008" />

===Long-term effects===
{{See also|Psychedelic microdosing#Cardiovascular toxicity}}

A potential risk of frequent repeated long-term use of LSD and other serotonergic psychedelics is [[cardiac fibrosis]] and [[cardiac valvulopathy|valvulopathy]] due to [[serotonin]] [[5-HT2B receptor|5-HT<sub>2B</sub> receptor]] [[agonist|agonism]].<ref name="TagenMantuanivanHeerden2023">{{cite journal | vauthors = Tagen M, Mantuani D, van Heerden L, Holstein A, Klumpers LE, Knowles R | title = The risk of chronic psychedelic and MDMA microdosing for valvular heart disease | journal = J Psychopharmacol | volume = 37 | issue = 9 | pages = 876–890 | date = September 2023 | pmid = 37572027 | doi = 10.1177/02698811231190865 | url = }}</ref><ref name="RouaudCalderHasler2024">{{cite journal | vauthors = Rouaud A, Calder AE, Hasler G | title = Microdosing psychedelics and the risk of cardiac fibrosis and valvulopathy: Comparison to known cardiotoxins | journal = J Psychopharmacol | volume = 38 | issue = 3 | pages = 217–224 | date = March 2024 | pmid = 38214279 | pmc = 10944580 | doi = 10.1177/02698811231225609 | url = }}</ref><ref name="NahlawiPtaszekRuskin2025">{{cite journal | vauthors = Nahlawi A, Ptaszek LM, Ruskin JN | title = Cardiovascular effects and safety of classic psychedelics | journal = Nat Cardiovasc Res | volume = 4 | issue = 2 | pages = 131–144 | date = February 2025 | pmid = 39910289 | doi = 10.1038/s44161-025-00608-2 | url = }}</ref><ref name="Wsół2023">{{cite journal | vauthors = Wsół A | title = Cardiovascular safety of psychedelic medicine: current status and future directions | journal = Pharmacol Rep | volume = 75 | issue = 6 | pages = 1362–1380 | date = December 2023 | pmid = 37874530 | pmc = 10661823 | doi = 10.1007/s43440-023-00539-4 | url = }}</ref><ref name="McIntyre2023">{{cite journal | vauthors = McIntyre RS | title = Serotonin 5-HT2B receptor agonism and valvular heart disease: implications for the development of psilocybin and related agents | journal = Expert Opin Drug Saf | volume = 22 | issue = 10 | pages = 881–883 | date = 2023 | pmid = 37581427 | doi = 10.1080/14740338.2023.2248883 | url = }}</ref> This may also be the case with [[microdosing]].<ref name="TagenMantuanivanHeerden2023" /><ref name="RouaudCalderHasler2024" /><ref name="NahlawiPtaszekRuskin2025" /> However, the risks are theoretical, and more research is needed to see if these complications can actually occur with psychedelics.<ref name="TagenMantuanivanHeerden2023" /><ref name="Wsół2023" /> A preliminary [[animal study]] found that chronic microdosing of LSD did not result in heart structure changes or valvulopathy in rodents.<ref name="EffingerKingCalderon2024">{{cite journal | vauthors = Effinger D, King J, Calderon J, Strong J, Thompson S | title = ACNP 63rd Annual Meeting: Poster Abstracts P609-P914: P680. Assessing the Potential Cardiovascular Risk of Microdosing Lysergic Acid Diethylamide in Mice | journal = Neuropsychopharmacology | volume = 49 | issue = Suppl 1 | pages = 418–594 (459–459) | date = December 2024 | pmid = 39643635 | doi = 10.1038/s41386-024-02013-y | url = | doi-access = free }}</ref> Research appears to be mixed on whether LSD is a potent serotonin 5-HT<sub>2B</sub> receptor agonist or not, with some studies finding it to be essentially inactive.<ref name="LuethiLiecthi2021">{{cite book | vauthors = Luethi D, Liechti ME | title=5-HT2B Receptors | chapter=Drugs of Abuse Affecting 5-HT2B Receptors | series=The Receptors | publisher=Springer International Publishing | publication-place=Cham | volume=35 | date=2021 | isbn=978-3-030-55919-9 | doi=10.1007/978-3-030-55920-5_16 | pages=277–289}}</ref>

==Interactions==
{{See also|Psychedelic drug#Interactions|Trip killer#Serotonergic psychedelic antidotes}}

Some psychedelics, including LSD, are [[drug metabolism|metabolized]] by the [[cytochrome P450]] [[enzyme]] [[CYP2D6]]. Concurrent use of [[selective serotonin reuptake inhibitor]]s (SSRIs), some of which are [[potency (pharmacology)|potent]] [[enzyme inhibitor|inhibitor]]s of CYP2D6, with LSD may heighten the risk of [[serotonin syndrome]].<ref name="drug-interaction"/>{{rp|145}} Chronic usage of SSRIs, [[tricyclic antidepressant]]s (TCAs), and [[monoamine oxidase inhibitor]]s (MAOIs) is believed to diminish the subjective effects of psychedelics, likely due to [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]] [[receptor downregulation|downregulation or desensitization]] induced by elevated [[serotonin]] levels.<ref name="PassieHalpernStrichtenoth2008" /><ref name="RachedCampanaFiani2026" /><ref name="drug-interaction"/>{{rp|145}} Contrary to the preceding notions however, a clinical study found that administration of LSD to people taking [[paroxetine]], an SSRI and strong CYP2D6 inhibitor, increased LSD exposure by about 1.5-fold, was well-tolerated, and did not modify the pleasant subjective effects or physiological effects of LSD, whereas negative effects of LSD, including "bad drug effect", [[anxiety]], and [[nausea]], were reduced.<ref name="BeckerHumbert-DrozMueller2025">{{cite journal | vauthors = Becker AM, Humbert-Droz M, Mueller L, Jelušić A, Tolev A, Straumann I, Avedisian I, Erne L, Thomann J, Luethi D, Grünblatt E, Meyer Zu Schwabedissen H, Liechti ME | title = Acute Effects and Pharmacokinetics of LSD after Paroxetine or Placebo Pre-Administration in a Randomized, Double-Blind, Cross-Over Phase I Trial | journal = Clin Pharmacol Ther | volume = 117| issue = 6| pages = 1784–1792| date = February 2025 | pmid = 40022427 | doi = 10.1002/cpt.3618 | url = | doi-access = free | pmc = 12087691 }}</ref> Similarly, a clinical study with LSD found that LSD levels were 75% higher in people with non-functional CYP2D6 ([[poor metabolizer]]s) compared to those with functional CYP2D6.<ref name="HalmanKongSarris2024">{{Cite journal |vauthors=Halman A, Kong G, Sarris J, Perkins D |date=January 2024 |title=Drug-drug interactions involving classic psychedelics: A systematic review |journal=J Psychopharmacol |volume=38 |issue=1 |pages=3–18 |doi=10.1177/02698811231211219 |pmc=10851641 |pmid=37982394}}</ref><ref name="VizeliStraumannHolze2021">{{cite journal | vauthors = Vizeli P, Straumann I, Holze F, Schmid Y, Dolder PC, Liechti ME | title = Genetic influence of CYP2D6 on pharmacokinetics and acute subjective effects of LSD in a pooled analysis | journal = Sci Rep | volume = 11 | issue = 1 | article-number = 10851 | date = May 2021 | pmid = 34035391 | pmc = 8149637 | doi = 10.1038/s41598-021-90343-y | bibcode = 2021NatSR..1110851V | url = }}</ref> In contrast to certain other psychedelics, MAOIs do not inhibit the [[drug metabolism|metabolism]] of or potentiate the effects of LSD and instead reduce its effects.<ref name="RachedCampanaFiani2026" /><ref name="PassieHalpernStrichtenoth2008" /> Interactions between psychedelics and [[antipsychotic]]s or [[anticonvulsant]]s are not well-documented; however, co-use with [[mood stabilizer]]s like [[lithium (medication)|lithium]] may induce [[seizure]]s and [[dissociative disorder|dissociative effects]], particularly in individuals with [[bipolar disorder]].<ref name="drug-interaction"/>{{rp|146}}<ref>{{cite journal |journal=Drug and Alcohol Dependence |volume=239 |article-number=109586 |vauthors=Simonsson O, Goldberg SB, Chambers R, Osika W, Long DM, Hendricks PS |date=1 October 2022 |pmid=35981469 |pmc=9627432 |title=Prevalence and associations of classic psychedelic-related seizures in a population-based sample |doi=10.1016/j.drugalcdep.2022.109586}}</ref><ref>{{cite journal |year=1967 |journal=Western Journal of Medicine |vauthors=Fisher D, Ungerleider J |pmid=4962683 |pmc=1502729 |volume=106 |issue=3 |pages=201–211 |title=Grand mal seizures following ingestion of LSD}}</ref> Lithium notably intensifies LSD reactions, potentially leading to acute comatose states when combined.<ref name="PassieHalpernStrichtenoth2008" />

==Overdose==
LSD at typical [[recreational drug|recreational]] doses (~50–250{{nbsp}}μg) is considered to be very [[drug safety|safe]] in terms of [[toxicity]], with not a single toxicity-related death having been reported at such doses despite many millions of exposures.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /><ref name="Henríquez-Hernández2023" /> In addition, LSD is considered to be a relatively non-toxic drug in [[overdose]].<ref name="Thomas2024">{{cite book | vauthors = Thomas K | title=Psychedelic Harm Reduction | chapter=Toxicology and Pharmacological Interactions of Classic Psychedelics | series=Current Topics in Behavioral Neurosciences | publisher=Springer Berlin Heidelberg | publication-place=Berlin, Heidelberg | date=2024 | volume=77 | pages=43–62 | doi=10.1007/7854_2024_508 | chapter-url=https://link.springer.com/10.1007/7854_2024_508 | access-date=14 May 2025 | pmid=39042251 | isbn=978-3-032-21106-4 }}</ref><ref name="NicholsGrob2018">{{cite journal | vauthors = Nichols DE, Grob CS | title = Is LSD toxic? | journal = Forensic Sci Int | volume = 284 | issue = | pages = 141–145 | date = March 2018 | pmid = 29408722 | doi = 10.1016/j.forsciint.2018.01.006 | url = }}</ref><ref name="Henríquez-Hernández2023">{{cite journal | vauthors = Henríquez-Hernández LA, Rojas-Hernández J, Quintana-Hernández DJ, Borkel LF | title = Hofmann vs. Paracelsus: Do Psychedelics Defy the Basics of Toxicology?-A Systematic Review of the Main Ergolamines, Simple Tryptamines, and Phenylethylamines | journal = Toxics | volume = 11 | issue = 2 | date = February 2023 | page = 148 | pmid = 36851023 | pmc = 9963058 | doi = 10.3390/toxics11020148 | doi-access = free | bibcode = 2023Toxic..11..148H | url = }}</ref><ref name="PassieHalpernStrichtenoth2008" /> It is estimated, based on [[animal study|animal studies]] and human [[case report]]s, that the [[lethal dose]] of LSD in humans is approximately 100{{nbsp}}mg, or about 1,000{{nbsp}}times the usual recreational dose of 100{{nbsp}}μg.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /> There have been a handful of reported cases of fatal overdose with LSD as of 2024.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /><ref name="Henríquez-Hernández2023" /><ref name="PassieHalpernStrichtenoth2008" /> However, critical review of the literature by [[David E. Nichols]] found that of five identified cases, one was not consistent with the effects of LSD but instead may have been another drug like [[25I-NBOMe]], two involved normal doses of LSD in individuals who were placed in [[hogtie|maximal physical restraint]] (hogtied) by police followed by presumed [[positional asphyxia]] and fatal cardiovascular collapse (hogtying being a practice that is associated with accidental death generally). Two were associated with massive LSD overdose involving doses of possibly more than 300{{nbsp}}mg.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /> Besides death due to toxicity, LSD is rarely associated with death via [[suicide]], [[accident]]s, or [[violence|violent encounter]]s due to induction of abnormal behavior.<ref name="NicholsGrob2018" /><ref name="Henríquez-Hernández2023" />

In one well-known 1974 [[case series]], 8{{nbsp}}people accidentally [[insufflation|insufflated]] two "lines" of nearly pure LSD powder that they thought were [[cocaine]].<ref name="Thomas2024" /><ref name="NicholsGrob2018" /><ref name="PassieHalpernStrichtenoth2008" /><ref name="KlockBoernerBecker1974">{{cite journal | vauthors = Klock JC, Boerner U, Becker CE | title = Coma, hyperthermia and bleeding associated with massive LSD overdose. A report of eight cases | journal = West J Med | volume = 120 | issue = 3 | pages = 183–188 | date = March 1974 | pmid = 4816396 | pmc = 1129381 | doi = | url = }}</ref><ref name="KlockBoerner1975">{{cite journal | vauthors = Klock JC, Boerner U, Becker CE | title = Coma, hyperthermia, and bleeding associated with massive LSD overdose, a report of eight cases | journal = Clin Toxicol | volume = 8 | issue = 2 | pages = 191–203 | date = 1975 | pmid = 1149410 | doi = 10.3109/15563657508988063 | url = }}</ref> The exact doses of LSD were unknown, but were considered to be massive.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /><ref name="PassieHalpernStrichtenoth2008" /> For context, a typical "line" of cocaine for insufflation is 50 to 100{{nbsp}}mg.<ref name="GoldsteinDesLauriersBurda2009">{{cite journal | vauthors = Goldstein RA, DesLauriers C, Burda A, Johnson-Arbor K | title = Cocaine: history, social implications, and toxicity: a review | journal = Semin Diagn Pathol | volume = 26 | issue = 1 | pages = 10–17 | date = February 2009 | pmid = 19292024 | doi = 10.1053/j.semdp.2008.12.001 | url = | quote = When "snorted," a typical "line" of cocaine contains approximately 50-100 mg of parent compound, although it is often "cut" or adulterated with other substances.20}}</ref> The individuals reported to the hospital within 10 to 15{{nbsp}}minutes, with five of them [[coma]]tose, three requiring [[intubation]] and [[mechanical ventilation]], and the conscious individuals experiencing severe [[hallucinogen]]ic effects, among other toxic symptoms.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /><ref name="PassieHalpernStrichtenoth2008" /><ref name="KlockBoerner1975" /> All of them completely recovered within 12{{nbsp}}hours and there were no deaths.<ref name="Thomas2024" /><ref name="NicholsGrob2018" /><ref name="PassieHalpernStrichtenoth2008" /><ref name="KlockBoerner1975" /> A subsequent 2020 case similarly involved accidental insufflation of a confirmed 55{{nbsp}}mg dose of LSD instead of cocaine, which was without adverse health consequences.<ref name="Henríquez-Hernández2023" /><ref name="HadenWoods2020">{{cite journal | vauthors = Haden M, Woods B | title = LSD Overdoses: Three Case Reports | journal = J Stud Alcohol Drugs | volume = 81 | issue = 1 | pages = 115–118 | date = January 2020 | pmid = 32048609 | doi = 10.15288/jsad.2020.81.115| url = }}</ref> In other reports, a 5{{nbsp}}mg overdose of LSD produced severe [[nausea]] and [[vomiting]] along with severe behavioral disturbances,<ref name="Shulgin1976" /><ref name="ReynoldsPeterson1966">{{cite journal | vauthors = Reynolds HH, Peterson GK | title = Psychophysiological effects of a large non-experimental dose of LSD-25 | journal = Psychol Rep | volume = 19 | issue = 1 | pages = 287–290 | date = August 1966 | pmid = 5942100 | doi = 10.2466/pr0.1966.19.1.287 | url = }}</ref> while a 10{{nbsp}}mg overdose was also non-fatal.<ref name="BrimblecombePinder1975" /><ref name="Cohen1971">{{cite book | vauthors = Cohen S | title=Progress in Drug Research / Fortschritte der Arzneimittelforschung / Progrès des Recherches Pharmaceutiques | chapter=The Psychotomimetic Agents | publisher=Birkhäuser Basel | publication-place=Basel | date=1971 | isbn=978-3-0348-7080-1 | doi=10.1007/978-3-0348-7078-8_2 | chapter-url=http://link.springer.com/10.1007/978-3-0348-7078-8_2 | access-date=2 June 2025 | pages=68–102}}</ref>

Despite acting as [[binding selectivity|non-selective]] [[serotonin receptor agonist]]s, major psychedelics like LSD and [[psilocybin]] do not cause [[serotonin syndrome]] even with extreme overdose.<ref name="MalcolmThomas2022">{{cite journal | vauthors = Malcolm B, Thomas K | title = Serotonin toxicity of serotonergic psychedelics | journal = Psychopharmacology (Berl) | volume = 239 | issue = 6 | pages = 1881–1891 | date = June 2022 | pmid = 34251464 | doi = 10.1007/s00213-021-05876-x | url = }}</ref><ref name="TapThomasPáleníček2025">{{cite journal | vauthors = Tap SC, Thomas K, Páleníček T, Stenbæk DS, Oliveira-Maia AJ, van Dalfsen J, Schoevers R | title = Concomitant use of antidepressants and classic psychedelics: A scoping review | journal = J Psychopharmacol | volume = 39| issue = 10 | date = September 2025 | article-number = 02698811251368360 | pmid = 40937732 | doi = 10.1177/02698811251368360 | pmc = 12572353 | url = | quote = Importantly, the idea of increased risk for developing serotonin syndrome and/or serotonin toxicity, when [antidepressants (ADs)] are co-administered with high doses of psychedelics, has recently been challenged, in part because classic psychedelics are partial agonists of the 5-HT2A receptor and would also compete for serotonin binding (Malcolm and Thomas, 2022; Rickli et al., 2016; Sarparast et al., 2022). Based on this clinical rationale, the concomitant use of ADs and classic psychedelics may be preferred, or patients could temporarily reduce the dose of ADs around dosing days with psychedelics to have minimal interactions. Simultaneously, the competition for 5-HT2A receptors could impede the biological action of psychedelics during concomitant use of ADs and potentially limit efficacy (Halman et al., 2024), particularly as the 5-HT2A receptor induces neuroplasticity (Cameron et al., 2023; Ly et al., 2018; Vargas et al., 2023).}}</ref> This is thought to be because they act as [[partial agonist]]s of [[serotonin receptor]]s like the serotonin [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]] relative to serotonin itself.<ref name="MalcolmThomas2022" /><ref name="TapThomasPáleníček2025" /> Conversely, [[NBOMe]] psychedelics like [[25I-NBOMe]] are more [[intrinsic activity|efficacious]] and have been uniquely associated with serotonin syndrome-like toxicity.<ref name="Thomas2024" /> A 2018 retrospective analysis of 3,554 LSD-only exposures reported to [[poison control center]]s in the [[United States]] between 2000 and 2016 found that serious toxicity was infrequent.<ref name="Thomas2024" /><ref name="LeonardAndersonKlein-Schwartz2018">{{cite journal | vauthors = Leonard JB, Anderson B, Klein-Schwartz W | title = Does getting high hurt? Characterization of cases of LSD and psilocybin-containing mushroom exposures to national poison centers between 2000 and 2016 | journal = J Psychopharmacol | volume = 32 | issue = 12 | pages = 1286–1294 | date = December 2018 | pmid = 30182795 | doi = 10.1177/0269881118793086 | url = }}</ref> Common adverse effects (2.4–42%) included [[psychomotor agitation|agitation]] or [[irritability]], [[tachycardia]], [[hallucination]]s or [[delusion]]s, [[mental confusion|confusion]], [[mydriasis|pupil dilation]], [[hypertension]], [[drowsiness]] or [[lethargy]], elevated [[creatine phosphokinase]] (CPK), [[nausea]] and [[vomiting]], and others.<ref name="LeonardAndersonKlein-Schwartz2018" /> Selected serious adverse effects included [[fever]] or [[hyperthermia]] in 3.8%, single [[seizure]] in 2.4%, [[coma]] in 1.4%, elevated [[creatinine]] in 1.4%, multiple seizures in 1.2%, [[rhabdomyolysis]] in 1.1%, [[respiratory depression]] in 0.9%, [[cardiac conduction disorder]] in 0.5%, and [[status epilepticus]] in 0.4%.<ref name="Thomas2024" /><ref name="LeonardAndersonKlein-Schwartz2018" /> There is a case report of severe [[neurological disorder|neurological sequelae]] following a single typical recreational dose of LSD involving seizure and [[cardiorespiratory arrest]].<ref name="RudinLiechtiLuethi2021">{{cite journal | vauthors = Rudin D, Liechti ME, Luethi D | title = Molecular and clinical aspects of potential neurotoxicity induced by new psychoactive stimulants and psychedelics | journal = Exp Neurol | volume = 343 | issue = | article-number = 113778 | date = September 2021 | pmid = 34090893 | doi = 10.1016/j.expneurol.2021.113778 | url = }}</ref><ref name="AakerøyBredeStølen2021">{{cite journal | vauthors = Aakerøy R, Brede WR, Stølen SB, Krabseth HM, Michelsen LS, Andreassen TN, Ader T, Frost J, Slettom G, Steihaug OM, Slørdal L | title = Severe Neurological Sequelae after a Recreational Dose of LSD | journal = J Anal Toxicol | volume = 45 | issue = 7 | pages = e1–e3 | date = August 2021 | pmid = 33031536 | pmc = 8363806 | doi = 10.1093/jat/bkaa145 | url = }}</ref> In general, psychedelics like LSD may rarely cause seizures in some individuals.<ref name="FreidelKreuderRabinovitch2023">{{cite journal | vauthors = Freidel N, Kreuder L, Rabinovitch BS, Chen FY, Huang RS, Lewis EC | title = Psychedelics, epilepsy, and seizures: a review | journal = Front Pharmacol | volume = 14 | issue = | article-number = 1326815 | date = 2023 | pmid = 38283836 | pmc = 10811552 | doi = 10.3389/fphar.2023.1326815 | doi-access = free | url = }}</ref><ref name="Soto-AngonaForteaFortea2024">{{cite journal | vauthors = Soto-Angona Ó, Fortea A, Fortea L, Martínez-Ramírez M, Santamarina E, López FJ, Knudsen GM, Ona G | title = Do classic psychedelics increase the risk of seizures? A scoping review | journal = Eur Neuropsychopharmacol | volume = 85 | issue = | pages = 35–42 | date = August 2024 | pmid = 38917636 | doi = 10.1016/j.euroneuro.2024.05.002 | url = }}</ref>

The [[median lethal dose]] (LD<sub>50</sub>) of LSD in animals varies and is 50 to 60{{nbsp}}mg/kg in mice, 16.5{{nbsp}}mg/kg in rats, and 0.3{{nbsp}}mg/kg in rabbits all given by [[injection (medicine)|injection]].<ref name="Henríquez-Hernández2023" /> A well-known 1962 instance of an elephant named Tusko given 297{{nbsp}}mg (~0.1{{nbsp}}mg/kg) LSD by [[intramuscular injection]] proved fatal.<ref name="Grob_2022a">{{cite book | vauthors = Grob C, Grigsby J | title = Handbook of Medical Hallucinogens | page = 81 | year = 2022 | publisher = Guilford Publications | isbn = 978-1-4625-5189-7 | url = https://books.google.com/books?id=r46ZEAAAQBAJ&pg=PA81 | access-date = 10 July 2025 }}</ref><ref name="Henríquez-Hernández2023" /><ref name="Cohen1971" /><ref name="West_1962">{{cite journal | vauthors = West LJ, Pierce CM, Thomas WD | title = Lysergic Acid Diethylamide: Its Effects on a Male Asiatic Elephant | journal = Science | location = New York, N.Y. | volume = 138 | issue = 3545 | pages = 1100–1103 | date = December 1962 | pmid = 17772968 | doi = 10.1126/science.138.3545.1100 | bibcode = 1962Sci...138.1100J }}</ref> These findings suggest that elephants may be much more sensitive to LSD in overdose than humans and other species.<ref name="Grob_2022a"/><ref name="Henríquez-Hernández2023" /> However, this instance has been mired in criticism and controversy due to miscalculation of LSD dose and concomitant post-LSD administration of [[promazine]] and [[pentobarbital]].<ref name="Grob_2022a" /><ref name="Siegel_1984" /> The experiment was repeated in two elephants with similar doses of LSD in 1984 without incident.<ref name="Grob_2022a" /><ref name="Henríquez-Hernández2023" /><ref name="Siegel_1984">{{cite journal | vauthors = Siegel RK | title = LSD-induced effects in elephants: Comparisons with musth behavior | journal = Bulletin of the Psychonomic Society | volume = 22 | issue = 1 | pages = 53–56 | date = 1984 | doi = 10.3758/BF03333759 | issn = 0090-5054 | doi-access = free | url = https://link.springer.com/content/pdf/10.3758%2FBF03333759.pdf | access-date = 10 July 2025 }}</ref>

Massive doses of LSD are largely managed by [[symptomatic treatment]]s, and [[psychomotor agitation|agitation]] can be addressed with [[benzodiazepine]]s.<ref name="Medscape">{{EMedicine|article|1011615|LSD Toxicity Treatment & Management|treatment}}</ref><ref name="ZawilskaKacelaAdamowicz2020" /> Reassurance in a [[set and setting|calm, safe environment]] is beneficial.<ref name="Hartogsohn2017">{{Cite journal |vauthors=Hartogsohn I |date=2017 |title=Constructing drug effects: A history of set and setting |journal=Drug Science, Policy and Law |language=en |volume=3 |article-number=2050324516683325 |doi=10.1177/2050324516683325 |s2cid=53373205 |issn=2050-3245 |doi-access=free}}</ref> [[Antipsychotic]]s such as [[haloperidol]] are not recommended as they may have [[adverse effect]]s.<ref name="Medscape" /> [[Gastric lavage|Gastrointestinal decontamination]] with [[activated charcoal (medication)|activated charcoal]] is of little use due to the rapid [[absorption (pharmacokinetics)|absorption]] of LSD, unless performed within 30 to 60{{Nbsp}}minutes of ingesting exceedingly huge amounts.<ref name="Medscape" /> Administration of [[anticoagulants]], [[vasodilators]], and [[sympatholytics]] may be useful for treating [[ergotism]].<ref name="Medscape" />{{Better source needed|date=July 2025}}

===LSD substitute overdose===
Although LSD is relatively safe in overdose, [[25-NB]] (NBOMe) psychedelics like [[25I-NBOMe]] and [[25B-NBOMe]] are often sold as "LSD" and are highly toxic in overdose, with many reported severe intoxications and deaths.<ref name="SuzukiDekkerValenti2015">{{cite journal | vauthors = Suzuki J, Dekker MA, Valenti ES, Arbelo Cruz FA, Correa AM, Poklis JL, Poklis A | title = Toxicities associated with NBOMe ingestion-a novel class of potent hallucinogens: a review of the literature | journal = Psychosomatics | volume = 56 | issue = 2 | pages = 129–139 | date = 2015 | pmid = 25659919 | pmc = 4355190 | doi = 10.1016/j.psym.2014.11.002 | url = }}</ref><ref name="ZawilskaKacelaAdamowicz2020">{{cite journal | vauthors = Zawilska JB, Kacela M, Adamowicz P | title = NBOMes-Highly Potent and Toxic Alternatives of LSD | journal = Front Neurosci | volume = 14 | issue = | article-number = 78 | date = 2020 | pmid = 32174803 | pmc = 7054380 | doi = 10.3389/fnins.2020.00078 | doi-access = free | url = }}</ref><ref name="HerianSwit2023">{{cite journal | vauthors = Herian M, Świt P | title = 25X-NBOMe compounds - chemistry, pharmacology and toxicology. A comprehensive review | journal = Crit Rev Toxicol | volume = 53 | issue = 1 | pages = 15–33 | date = January 2023 | pmid = 37115704 | doi = 10.1080/10408444.2023.2194907 | url = }}</ref> Owing to their high [[potency (pharmacology)|potency]] analogous to LSD, these drugs are also regularly sold as "LSD" in [[blotter paper]]s.<ref name="pmid30261175">{{cite journal |journal=Biochemical Pharmacology |vauthors=Eshleman AJ, Wolfrum KM, Reed JF, Kim SO, Johnson RA, Janowsky A |title=Neurochemical pharmacology of psychoactive substituted N-benzylphenethylamines: High potency agonists at 5-HT2A receptors |doi=10.1016/j.bcp.2018.09.024 |pmid=30261175 |pmc=6298744 |volume=158 |pages=27–34 |date=December 2018}}</ref><ref>{{cite journal |journal=Journal of Analytical Toxicology |doi=10.1093/jat/bkv073 |pmc=4570937 |pmid=26378135 |title=Analysis of 25I-NBOMe, 25B-NBOMe, 25C-NBOMe and Other Dimethoxyphenyl-N-[(2-Methoxyphenyl) Methyl]Ethanamine Derivatives on Blotter Paper |vauthors=Poklis JL, Raso SA, Alford KN, Poklis A, Peace MR |date=Oct 2015 |volume=39 |issue=8 |pages=617–623}}</ref> Fatalities involved in NBOMe intoxication suggest that a significant number of individuals ingested the substance which they believed was LSD,<ref name="pmid31915427">{{cite journal |journal=Frontiers in Pharmacology |date=12 December 2019 |vauthors=Miliano C, Marti M, Pintori N, Castelli MP, Tirri M, Arfè R, De Luca MA |title=Neurochemical and Behavioral Profiling in Male and Female Rats of the Psychedelic Agent 25I-NBOMe |volume=10 |article-number=1406 |pmid=31915427 |pmc=6921684 |doi=10.3389/fphar.2019.01406 |doi-access=free}}</ref> and researchers report that "users familiar with LSD may have a false sense of security when ingesting NBOMe inadvertently".<ref name="Lipow22">{{cite journal |journal=Transformative Medicine |title=NBOMe Toxicity and Fatalities: A Review of the Literature |volume=1 |issue=1 |date=March 2022 |vauthors=Lipow M, Kaleem SZ, Espiridion E |pages=12–18 |s2cid=247888583 |doi=10.54299/tmed/msot8578 |doi-access=free |issn=2831-8978}}</ref> Researchers state that the alleged physiological toxicity of LSD is likely due to psychoactive substances other than LSD.<ref name="NicholsGrob2021"/>

NBOMe compounds are reported to have a bitter taste,<ref name="Lipow22"/> are not active orally,{{efn|The [[Potency (pharmacology)|potency]] of ''N''-benzylphenethylamines via buccal, sublingual, or nasal absorption is 50–100 greater (by weight) than oral route compared to the parent [[2C-x]] compounds.<ref name="pmid24519542">{{cite journal |journal=Neurochemical Research |date=14 February 2014 |vauthors=Leth-Petersen S, Bundgaard C, Hansen M, Carnerup MA, Kehler J, Kristensen JL |title=Correlating the Metabolic Stability of Psychedelic 5-HT2A Agonists with Anecdotal Reports of Human Oral Bioavailability |volume=39 |issue=10 |pages=2018–2023 |doi=10.1007/s11064-014-1253-y |pmid=24519542| s2cid=254857910}}</ref> Researches hypothesize the low oral metabolic stability of ''N''-benzylphenethylamines is likely causing the low bioavailability on the oral route, although the metabolic profile of this compounds remains unpredictable; therefore researches state that the fatalities linked to these substances may partly be explained by differences in the metabolism between individuals.<ref name="pmid24519542"/>}} and are usually taken [[sublingually]].<ref name="pmid28097528">{{cite book |title=Neuropharmacology of New Psychoactive Substances |vauthors=Halberstadt AL |doi=10.1007/7854_2016_64 |date=18 January 2017 |isbn=978-3-319-52444-3 |publisher=Springer |chapter=Pharmacology and Toxicology of N-Benzylphenethylamine ("NBOMe") Hallucinogens |series=Current Topics in Behavioral Neurosciences |volume=32 |pages=283–311 |pmid=28097528}}</ref> When NBOMes are administered sublingually, [[numbness]] of the tongue and mouth followed by a metallic chemical taste was observed, and researchers describe this physical side effect as one of the main discriminants between NBOMe compounds and LSD.<ref>{{cite journal |vauthors=Duffau B, Camargo C, Kogan M, Fuentes E, Kennedy Cassels B |journal=Journal of Chromatographic Science |volume=54 |issue=7 |date=August 2016 |pages=1153–1158 |title=Analysis of 25 C NBOMe in Seized Blotters by HPTLC and GC–MS |pmc=4941995 |pmid=27406128 |doi=10.1093/chromsci/bmw095 |doi-access=free}}</ref><ref>{{cite journal |pmid=25105138 |pmc=4106087 |doi=10.1155/2014/734749 |title=25C-NBOMe: preliminary data on pharmacology, psychoactive effects, and toxicity of a new potent and dangerous hallucinogenic drug |journal=BioMed Research International |date=3 July 2014 |vauthors=Francesco SB, Ornella C, Gabriella A, Giuseppe V, Rita S, Flaminia BP, Eduardo C, Pierluigi S, Giovanni M, Guiseppe B, Fabrizio S |volume=2014 |article-number=734749 |doi-access=free}}</ref><ref>{{cite book |title=Novel Psychoactive Substances: Classification, Pharmacology and Toxicology |chapter=Pharmacology and toxicology of N-Benzyl-phenylethylamines (25X-NBOMe) hallucinogens |vauthors=Potts AJ, ((Thomas SHL)), Hill SL |veditors=Dargan P, Wood D |doi=10.1016/B978-0-12-818788-3.00008-5 |isbn=978-0-12-818788-3 |pages=279–300 |edition=2nd |publisher=Academic Press |date=September 2021 |s2cid=240583877}}</ref> Despite its high potency, recreational doses of LSD have only produced low incidents of acute toxicity, but NBOMe compounds have extremely different safety profiles.<ref name="Lipow22"/><ref name="pmid35343858">{{cite journal |journal=[[Clinical Toxicology]] |title=A cluster of 25B-NBOH poisonings following exposure to powder sold as lysergic acid diethylamide (LSD) |vauthors=Ivory ST, Rotella J, Schumann J, Greene SL |pages=966–969 |date=28 March 2022 |volume=60 |issue=8 |doi=10.1080/15563650.2022.2053150 |pmid=35343858 |s2cid=247764056}}</ref> Testing with [[Ehrlich's reagent]] gives a positive result for LSD and a negative result for NBOMe compounds.<ref>{{Cite journal | vauthors = Díaz Moreno M, Alarcón Ayala N, Estrada Y, Morris V, Quintero J |date=November 2022 |title=Échele Cabeza as a harm reduction project and activist movement in Colombia |url=https://www.emerald.com/insight/content/doi/10.1108/DHS-07-2022-0026/full/html |journal=[[Drugs, Habits and Social Policy]] |language=en |volume=23 |issue=3 |pages=263–276 |doi=10.1108/DHS-07-2022-0026 |issn=2752-6739}}</ref><ref>{{cite journal | vauthors = Clancy L, Philp M, Shimmon R, Fu S | title = Development and validation of a color spot test method for the presumptive detection of 25-NBOMe compounds | journal = Drug Testing and Analysis | volume = 13 | issue = 5 | pages = 929–943 | date = May 2021 | pmid = 32744773 | doi = 10.1002/dta.2905 }}</ref>

==Pharmacology==
===Pharmacodynamics===
{| class="wikitable floatright" style="font-size:small;"
|+ {{Nowrap|Activities of LSD}}
|-
! [[Biological target|Target]] !! [[Affinity (pharmacology)|Affinity]] (K<sub>i</sub>, nM)
|-
| [[5-HT1A receptor|5-HT<sub>1A</sub>]] || 0.64–7.3 (K<sub>i</sub>)<br />6.4 ({{Abbrlink|EC<sub>50</sub>|half-maximal effective concentration}})<br />110% ({{Abbrlink|E<sub>max</sub>|maximal efficacy}})
|-
| [[5-HT1B receptor|5-HT<sub>1B</sub>]] || 3.9
|-
| [[5-HT1D receptor|5-HT<sub>1D</sub>]] || 3.9–14
|-
| [[5-HT1E receptor|5-HT<sub>1E</sub>]] || 93
|-
| [[5-HT1F receptor|5-HT<sub>1F</sub>]] || {{Abbr|ND|No data}}
|-
| [[5-HT2A receptor|5-HT<sub>2A</sub>]] || 0.47–21 (K<sub>i</sub>)<br />0.24–538 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}})<br />23–88% ({{Abbr|E<sub>max</sub>|maximal efficacy}})
|-
| [[5-HT2B receptor|5-HT<sub>2B</sub>]] || 0.98–30 (K<sub>i</sub>)<br />0.68–12,000 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}})<br />13–73% ({{Abbr|E<sub>max</sub>|maximal efficacy}})
|-
| [[5-HT2C receptor|5-HT<sub>2C</sub>]] || 1.1–48 (K<sub>i</sub>)<br />0.85–1,590 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}})<br />26–79% ({{Abbr|E<sub>max</sub>|maximal efficacy}})
|-
| [[5-HT3 receptor|5-HT<sub>3</sub>]] || >10,000
|-
| [[5-HT4 receptor|5-HT<sub>4</sub>]] || 1,000 (rat)
|-
| [[5-HT5A receptor|5-HT<sub>5A</sub>]] || 9.0
|-
| [[5-HT5B receptor|5-HT<sub>5B</sub>]] || 3.2 (rat)
|-
| [[5-HT6 receptor|5-HT<sub>6</sub>]] || 2.3–6.9
|-
| [[5-HT7 receptor|5-HT<sub>7</sub>]] || 6.3–6.6
|-
| [[Alpha-1A adrenergic receptor|α<sub>1A</sub>]] || 670–1,128
|-
| [[Alpha-1B adrenergic receptor|α<sub>1B</sub>]] || 8,677
|-
| [[Alpha-1D adrenergic receptor|α<sub>1D</sub>]] || {{Abbr|ND|No data}}
|-
| [[Alpha-2A adrenergic receptor|α<sub>2A</sub>]] || 12–46
|-
| [[Alpha-2B adrenergic receptor|α<sub>2B</sub>]], [[Alpha-2C adrenergic receptor|α<sub>2C</sub>]] || {{Abbr|ND|No data}}
|-
| [[Beta-1 adrenergic receptor|β<sub>1</sub>]] || 140–1,601
|-
| [[Beta-2 adrenergic receptor|β<sub>2</sub>]] || 740–3,461
|-
| [[Beta-3 adrenergic receptor|β<sub>3</sub>]] || {{Abbr|ND|No data}}
|-
| [[D1 receptor|D<sub>1</sub>]] || 155–340 (K<sub>i</sub>)<br />35–63 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}})<br />35–44% ({{Abbr|E<sub>max</sub>|maximal efficacy}})
|-
| [[D2 receptor|D<sub>2</sub>]] || 61–126
|-
| [[D3 receptor|D<sub>3</sub>]] || 27–60
|-
| [[D4 receptor|D<sub>4</sub>]] || 26–158
|-
| [[D5 receptor|D<sub>5</sub>]] || 75–344
|-
| [[H1 receptor|H<sub>1</sub>]] || 1,100–1,540
|-
| [[H2 receptor|H<sub>2</sub>]]–[[H4 receptor|H<sub>4</sub>]] || {{Abbr|ND|No data}}
|-
| [[Muscarinic acetylcholine M1 receptor|M<sub>1</sub>]]–[[Muscarinic acetylcholine M5 receptor|M<sub>5</sub>]] || {{Abbr|ND|No data}}
|-
| [[I1 receptor|I<sub>1</sub>]] || {{Abbr|ND|No data}}
|-
| [[Sigma-1 receptor|σ<sub>1</sub>]], [[Sigma-2 receptor|σ<sub>2</sub>]] || {{Abbr|ND|No data}}
|-
| [[Trace amine-associated receptor 1|TAAR1]] || 450 (K<sub>i</sub>) (rat)<br />10,000 (K<sub>i</sub>) (mouse)<br />1,400 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}}) (rat)<br />9,700 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}}) (mouse)<br />>20,000 ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}}) (human)
|-
| {{Abbrlink|SERT|Serotonin transporter}} || >30,000 (K<sub>i</sub>)<br />>100,000 ({{Abbrlink|IC<sub>50</sub>|half-maximal inhibitory concentration}})
|-
| {{Abbrlink|NET|Norepinephrine transporter}} || 5,600–>30,000 (K<sub>i</sub>)<br />>100,000 ({{Abbr|IC<sub>50</sub>|half-maximal inhibitory concentration}})
|-
| {{Abbrlink|DAT|Dopamine transporter}} || >30,000 (K<sub>i</sub>)<br />>100,000 ({{Abbr|IC<sub>50</sub>|half-maximal inhibitory concentration}})
|- class="sortbottom"
| colspan="2" style="width: 1px; background-color:var(--background-color-notice-subtle,#eaecf0); color:inherit; text-align: center;" | '''Notes:''' The smaller the value, the more avidly the drug binds to the site. All proteins are human unless otherwise noted. '''Refs:''' <ref name="PDSPKiDatabase">{{cite web | title=PDSP Database | website=UNC | url=https://pdsp.unc.edu/databases/pdsp.php?testFreeRadio=testFreeRadio&testLigand=lsd&kiAllRadio=all&doQuery=Submit+Query | language=zu | access-date=11 December 2024}}</ref><ref name="BindingDB">{{cite web | vauthors = Liu T | title=BindingDB BDBM21342 (4R,7R)-N,N-diethyl-6-methyl-6,11-diazatetracyclo[7.6.1.0^{2,7}.0^{12,16}]hexadeca-1(16),2,9,12,14-pentaene-4-carboxamide::CHEMBL263881::LSD::LSD 25::LSD,(+)::LSD,l-::Lysergic Acid Diethylamide::Lysergic Acid Diethylamide Tartrate::US20240166618, Compound LSD::[3H]-LSD::d-Isolysergic acid amide | website=BindingDB | url=https://www.bindingdb.org/rwd/bind/chemsearch/marvin/MolStructure.jsp?monomerid=21342 | access-date=11 December 2024}}</ref><ref name="HolzeSinghLiechti2024">{{cite journal | vauthors = Holze F, Singh N, Liechti ME, D'Souza DC | title = Serotonergic Psychedelics: A Comparative Review of Efficacy, Safety, Pharmacokinetics, and Binding Profile | journal = Biol Psychiatry Cogn Neurosci Neuroimaging | volume = 9 | issue = 5 | pages = 472–489 | date = May 2024 | pmid = 38301886 | doi = 10.1016/j.bpsc.2024.01.007 | url = | doi-access = free }}</ref><ref name="Ray2010">{{cite journal | vauthors = Ray TS | title = Psychedelics and the human receptorome | journal = PLOS ONE | volume = 5 | issue = 2 |article-number=e9019 | date = February 2010 | pmid = 20126400 | pmc = 2814854 | doi = 10.1371/journal.pone.0009019 | doi-access = free | bibcode = 2010PLoSO...5.9019R | url = }}</ref><ref name="RickliLuethiReinisch2015">{{cite journal | vauthors = Rickli A, Luethi D, Reinisch J, Buchy D, Hoener MC, Liechti ME | title = Receptor interaction profiles of novel N-2-methoxybenzyl (NBOMe) derivatives of 2,5-dimethoxy-substituted phenethylamines (2C drugs) | journal = Neuropharmacology | volume = 99 | issue = | pages = 546–553 | date = December 2015 | pmid = 26318099 | doi = 10.1016/j.neuropharm.2015.08.034 | url = http://edoc.unibas.ch/56163/1/20170921163006_59c3cceeb8e5d.pdf}}</ref><ref name="RickliMoningHoener2016">{{cite journal | vauthors = Rickli A, Moning OD, Hoener MC, Liechti ME | title = Receptor interaction profiles of novel psychoactive tryptamines compared with classic hallucinogens | journal = Eur Neuropsychopharmacol | volume = 26 | issue = 8 | pages = 1327–1337 | date = August 2016 | pmid = 27216487 | doi = 10.1016/j.euroneuro.2016.05.001 | url = http://edoc.unibas.ch/53326/1/20170117174852_587e4af45b658.pdf}}</ref><ref name="LuethiTrachselHoener2018">{{cite journal | vauthors = Luethi D, Trachsel D, Hoener MC, Liechti ME | title = Monoamine receptor interaction profiles of 4-thio-substituted phenethylamines (2C-T drugs) | journal = Neuropharmacology | volume = 134 | issue = Pt A | pages = 141–148 | date = May 2018 | pmid = 28720478 | doi = 10.1016/j.neuropharm.2017.07.012 | url = https://edoc.unibas.ch/57358/1/20170920150712_59c2680084ec5.pdf}}</ref><ref name="EshlemanForsterWolfrum2014">{{cite journal | vauthors = Eshleman AJ, Forster MJ, Wolfrum KM, Johnson RA, Janowsky A, Gatch MB | title = Behavioral and neurochemical pharmacology of six psychoactive substituted phenethylamines: mouse locomotion, rat drug discrimination and in vitro receptor and transporter binding and function | journal = Psychopharmacology (Berl) | volume = 231 | issue = 5 | pages = 875–888 | date = March 2014 | pmid = 24142203 | pmc = 3945162 | doi = 10.1007/s00213-013-3303-6 | url = https://www.researchgate.net/publication/258061356}}</ref><br /><ref name="JanowskyEshlemanJohnson2014">{{cite journal | vauthors = Janowsky A, Eshleman AJ, Johnson RA, Wolfrum KM, Hinrichs DJ, Yang J, Zabriskie TM, Smilkstein MJ, Riscoe MK | title = Mefloquine and psychotomimetics share neurotransmitter receptor and transporter interactions in vitro | journal = Psychopharmacology (Berl) | volume = 231 | issue = 14 | pages = 2771–2783 | date = July 2014 | pmid = 24488404 | pmc = 4097020 | doi = 10.1007/s00213-014-3446-0 | url = }}</ref><ref name="Wsół2023"/><ref name="EganGrindeDupre2000">{{cite journal | vauthors = Egan C, Grinde E, Dupre A, Roth BL, Hake M, Teitler M, Herrick-Davis K | title = Agonist high and low affinity state ratios predict drug intrinsic activity and a revised ternary complex mechanism at serotonin 5-HT(2A) and 5-HT(2C) receptors | journal = Synapse | volume = 35 | issue = 2 | pages = 144–150 | date = February 2000 | pmid = 10611640 | doi = 10.1002/(SICI)1098-2396(200002)35:2<144::AID-SYN7>3.0.CO;2-K | url = }}</ref><ref name="WackerWangMcCorvy2017">{{cite journal | vauthors = Wacker D, Wang S, McCorvy JD, Betz RM, Venkatakrishnan AJ, Levit A, Lansu K, Schools ZL, Che T, Nichols DE, Shoichet BK, Dror RO, Roth BL | title = Crystal Structure of an LSD-Bound Human Serotonin Receptor | journal = Cell | volume = 168 | issue = 3 | pages = 377–389.e12 | date = January 2017 | pmid = 28129538 | doi = 10.1016/j.cell.2016.12.033 | url = | pmc = 5289311 }}</ref><ref name="McCorvy2013">{{cite thesis | vauthors = McCorvy JD | title=Mapping the binding site of the 5-HT2A receptor using mutagenesis and ligand libraries: Insights into the molecular actions of psychedelics | degree = Ph.D. | publisher = Purdue University | via = Purdue e-Pubs | date=16 January 2013 | url=https://docs.lib.purdue.edu/dissertations/AAI3545320/ | archive-url=https://web.archive.org/web/20250325000000/https://docs.lib.purdue.edu/dissertations/AAI3545320/ | archive-date=25 March 2025 | quote=Table 5.2 Binding affinities using 3 H-LSD at 5-HT2A EL2 mutants [...] Table B.1 Binding affinities for 5-HT2A, 5-HT2C, 5-HT1A receptors using 3 H-LSD [...]}} [https://bitnest.netfirms.com/external/Theses/McCorvey2012 Alt URL]</ref><ref name="PorterBenwellLamb1999">{{cite journal | vauthors = Porter RH, Benwell KR, Lamb H, Malcolm CS, Allen NH, Revell DF, Adams DR, Sheardown MJ | title = Functional characterization of agonists at recombinant human 5-HT2A, 5-HT2B and 5-HT2C receptors in CHO-K1 cells | journal = Br J Pharmacol | volume = 128 | issue = 1 | pages = 13–20 | date = September 1999 | pmid = 10498829 | pmc = 1571597 | doi = 10.1038/sj.bjp.0702751 | url = }}</ref><ref name="GainetdinovHoenerBerry2018">{{cite journal | vauthors = Gainetdinov RR, Hoener MC, Berry MD | title = Trace Amines and Their Receptors | journal = Pharmacol Rev | volume = 70 | issue = 3 | pages = 549–620 | date = July 2018 | pmid = 29941461 | doi = 10.1124/pr.117.015305 | url = | doi-access = free }}</ref><ref name="SimmlerBuchyChaboz2016">{{cite journal | vauthors = Simmler LD, Buchy D, Chaboz S, Hoener MC, Liechti ME | title = In Vitro Characterization of Psychoactive Substances at Rat, Mouse, and Human Trace Amine-Associated Receptor 1 | journal = J Pharmacol Exp Ther | volume = 357 | issue = 1 | pages = 134–144 | date = April 2016 | pmid = 26791601 | doi = 10.1124/jpet.115.229765 | url = https://d1wqtxts1xzle7.cloudfront.net/74120533/eae6c6e62565b82d46b4d111bbea0f77b9c2-libre.pdf?1635931703=&response-content-disposition=inline%3B+filename%3DIn_Vitro_Characterization_of_Psychoactiv.pdf&Expires=1746838268&Signature=Sy4fJ90yUhxs68314NxYsW5PAaNrBGePRu35WRR4PIF-3YC7Z~sLdnCn5wfqqbLg9bDEGdt~oW55ugMP3D3jgA0BoRI~~GOb0NQOwrtfUEQK1PQs1uuN9qg5Y1ct8z5NsABm44RgtukkwRMdU6fO7OlfIsQ68hOiFk129Ll7UYqldxD2f1xhE2fTTfsxSpb8cMCJzHn7-ItqLdwnAUPFK7WggDIjmY1kCnaHLwIxMwdJCAq8L6DYzSTg7pZkbR8qlou~GXbTPQt~gYpyZTJp5hgW-7V6K5wLlQ7Z2xE7B0f9wEfuc1W1QNafg125Tr-vvAe4LEGKXV58bnn1bpfWKw__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA | archive-url = https://web.archive.org/web/20250509235235/https://d1wqtxts1xzle7.cloudfront.net/74120533/eae6c6e62565b82d46b4d111bbea0f77b9c2-libre.pdf?1635931703=&response-content-disposition=inline%3B+filename%3DIn_Vitro_Characterization_of_Psychoactiv.pdf&Expires=1746838268&Signature=Sy4fJ90yUhxs68314NxYsW5PAaNrBGePRu35WRR4PIF-3YC7Z~sLdnCn5wfqqbLg9bDEGdt~oW55ugMP3D3jgA0BoRI~~GOb0NQOwrtfUEQK1PQs1uuN9qg5Y1ct8z5NsABm44RgtukkwRMdU6fO7OlfIsQ68hOiFk129Ll7UYqldxD2f1xhE2fTTfsxSpb8cMCJzHn7-ItqLdwnAUPFK7WggDIjmY1kCnaHLwIxMwdJCAq8L6DYzSTg7pZkbR8qlou~GXbTPQt~gYpyZTJp5hgW-7V6K5wLlQ7Z2xE7B0f9wEfuc1W1QNafg125Tr-vvAe4LEGKXV58bnn1bpfWKw__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA | archive-date = 2025-05-09 }}</ref>
|}

LSD is a [[serotonergic psychedelic]] and acts as a [[binding selectivity|non-selective]] [[serotonin receptor modulator]].<ref name="Nichols2018a" /> It binds with high [[affinity (pharmacology)|affinity]] to most of the [[serotonin receptor]]s.<ref name="HolzeSinghLiechti2024" /> The [[psychedelic drug|psychedelic]] effects of LSD are thought to be mediated specifically by activation of the [[serotonin]] [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]].<ref name="Nichols2018a" /><ref name="HolzeSinghLiechti2024" /> However, the role of other serotonin receptors and [[biological target|target]]s in the effects of LSD cannot be ruled out and may be considered likely.<ref name="HalberstadtGeyer2011">{{cite journal | vauthors = Halberstadt AL, Geyer MA | title = Multiple receptors contribute to the behavioral effects of indoleamine hallucinogens | journal = Neuropharmacology | volume = 61 | issue = 3 | pages = 364–381 | date = September 2011 | pmid = 21256140 | pmc = 3110631 | doi = 10.1016/j.neuropharm.2011.01.017 | url = }}</ref> Uniquely among serotonergic psychedelics, LSD also shows potentially significant affinity for the [[dopamine receptor]]s, albeit much lower than for most of the serotonin receptors.<ref name="HolzeSinghLiechti2024" /><ref name="Marona-LewickaThistedNichols2005">{{cite journal | vauthors = Marona-Lewicka D, Thisted RA, Nichols DE | title = Distinct temporal phases in the behavioral pharmacology of LSD: dopamine D2 receptor-mediated effects in the rat and implications for psychosis | journal = Psychopharmacology | volume = 180 | issue = 3 | pages = 427–435 | date = July 2005 | pmid = 15723230 | doi = 10.1007/s00213-005-2183-9 | s2cid = 23565306 }}</ref>

LSD binds to most serotonin receptor subtypes except for the serotonin [[5-HT3 receptor|5-HT<sub>3</sub>]] and [[5-HT4 receptor|5-HT<sub>4</sub> receptor]]s.<ref name="HolzeSinghLiechti2024" /> However, some of these serotonin receptors may not be affected at typical brain concentrations of LSD.<ref name="Nichols2004" /> In humans, recreational doses of LSD may affect serotonin [[5-HT1A receptor|5-HT<sub>1A</sub>]], [[5-HT2A receptor|5-HT<sub>2A</sub>]], [[5-HT2B receptor|5-HT<sub>2B</sub>]], [[5-HT2C receptor|5-HT<sub>2C</sub>]], [[5-HT5A receptor|5-HT<sub>5A</sub>]], and [[5-HT6 receptor|5-HT<sub>6</sub> receptor]]s.<ref name="Aghajanian" /> Although not present in humans, serotonin [[5-HT5B receptor|5-HT<sub>5B</sub> receptor]]s found in rodents also have high affinity for LSD.<ref name="Nelson2004">{{cite journal |vauthors=Nelson DL |title=5-HT5 receptors |journal=Current Drug Targets. CNS and Neurological Disorders |volume=3 |issue=1 |pages=53–58 |date=February 2004 |pmid=14965244 |doi=10.2174/1568007043482606}}</ref> The psychedelic effects of LSD are attributed to activation of 5-HT<sub>2A</sub> receptors.<ref>{{cite journal |vauthors=Moreno JL, Holloway T, Albizu L, Sealfon SC, González-Maeso J |title=Metabotropic glutamate mGlu2 receptor is necessary for the pharmacological and behavioral effects induced by hallucinogenic 5-HT2A receptor agonists |journal=Neuroscience Letters |volume=493 |issue=3 |pages=76–79 |date=April 2011 |pmid=21276828 |pmc=3064746 |doi=10.1016/j.neulet.2011.01.046}}</ref> Many but not all serotonin 5-HT<sub>2A</sub> receptor [[agonist]]s are psychedelics, and serotonin 5-HT<sub>2A</sub> receptor [[receptor antagonist|antagonist]]s block the psychedelic effects of LSD. The drug exhibits pronounced [[functional selectivity]] or [[biased agonism]] at the serotonin 5-HT<sub>2A</sub> and 5-HT<sub>2C</sub> receptors in that it activates the [[signal transduction]] [[enzyme]] [[phospholipase A2]] (PLA2) instead of activating the enzyme [[phospholipase C]] (PLC) as the [[endogenous]] [[ligand (biochemistry)|ligand]] serotonin does, among other differences.<ref>{{cite journal |vauthors=Urban JD, Clarke WP, von Zastrow M, Nichols DE, Kobilka B, Weinstein H, Javitch JA, Roth BL, Christopoulos A, Sexton PM, Miller KJ, Spedding M, Mailman RB |title=Functional selectivity and classical concepts of quantitative pharmacology |journal=The Journal of Pharmacology and Experimental Therapeutics |volume=320 |issue=1 |pages=1–13 |date=January 2007 |pmid=16803859 |doi=10.1124/jpet.106.104463 |url=https://jpet.aspetjournals.org/content/320/1/1 |s2cid=447937 |access-date=June 11, 2023 |archive-date=June 11, 2023 |archive-url=https://web.archive.org/web/20230611010342/https://jpet.aspetjournals.org/content/320/1/1 |url-status=live }}</ref><ref name="BonniwellAlabadaliHennessey2025">{{cite journal | vauthors = Bonniwell EM, Alabdali R, Hennessey JJ, McKee JL, Cavalco NG, Lammers JC, Moore EJ, Franchini L, Orlandi C, McCorvy JD | title = Serotonin 5-HT2C Receptor Signaling Analysis Reveals Psychedelic Biased Agonism | journal = ACS Chem Neurosci | volume = 16 | issue = 19 | pages = 3899–3914 | date = October 2025 | pmid = 40944639 | doi = 10.1021/acschemneuro.5c00647 | pmc = 12629614 | url = }}</ref>

Exactly how LSD produces its effects is unknown, but it is thought that it may work in part by increasing [[glutamate (neurotransmitter)|glutamate]] release in the [[cerebral cortex]]<ref name="Nichols2004" /> and therefore [[Excitatory postsynaptic potential|excitation]] in this area, specifically in [[Cortical layers|layer V]].<ref>{{cite journal | vauthors = Aghajanian GK, Marek GJ | title = Serotonin and hallucinogens | journal = Neuropsychopharmacology | volume = 21 | issue = 2 Suppl | pages = 16S–23S | date = August 1999 | pmid = 10432484 | doi = 10.1016/S0893-133X(98)00135-3 | doi-access = free }}</ref> LSD, like many other drugs of recreational use, has been shown to activate [[DARPP-32]]-related pathways.<ref>{{cite journal | vauthors = Svenningsson P, Nairn AC, Greengard P | title = DARPP-32 mediates the actions of multiple drugs of abuse | journal = The AAPS Journal | volume = 7 | issue = 2 | pages = E353-60 | date = October 2005 | pmid = 16353915 | pmc = 2750972 | doi = 10.1208/aapsj070235 }}</ref> The drug enhances dopamine D<sub>2</sub> receptor [[protomer]] recognition and [[cell signaling|signaling]] of D<sub>2</sub>–5-HT<sub>2A</sub> [[heteromer]]ic receptor complexes,<ref name="pmid24309097">{{cite journal | vauthors = Borroto-Escuela DO, Romero-Fernandez W, Narvaez M, Oflijan J, Agnati LF, Fuxe K | title = Hallucinogenic 5-HT2AR agonists LSD and DOI enhance dopamine D2R protomer recognition and signaling of D2-5-HT2A heteroreceptor complexes | journal = Biochemical and Biophysical Research Communications | volume = 443 | issue = 1 | pages = 278–84 | date = January 2014 | pmid = 24309097 | doi = 10.1016/j.bbrc.2013.11.104 | bibcode = 2014BBRC..443..278B }}</ref> which may contribute to its psychotropic effects.<ref name="pmid24309097" /> LSD has been shown to have low affinity for [[histamine]] [[histamine H1 receptor|H<sub>1</sub> receptor]]s, displaying [[antihistamine]] effects, although the significance of this at doses used in humans is unknown.<ref>{{cite journal | vauthors = Green JP, Johnson CL, Weinstein H, Maayani S | title = Antagonism of histamine-activated adenylate cyclase in brain by D-lysergic acid diethylamide | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 74 | issue = 12 | pages = 5697–701 | date = December 1977 | pmid = 23536 | pmc = 431860 | doi = 10.1073/pnas.74.12.5697 | bibcode = 1977PNAS...74.5697G | doi-access = free }}</ref><ref name="synth2"/> [[David E. Nichols]] has suggested that there may be a pharmacological basis for some [[bad trip]]s with LSD.<ref name="NicholsBillacHarbit2026">{{cite conference | vauthors = Nichols D, Billac GB, Harbit RC, Smith JM | title = A Pharmacological Basis for Some Bad LSD Trips?: A 50+ Year Odyssey | conference = International Society for Research on Psychedelics (ISRP) 2026 | date = 1 March 2026 | url = https://static1.squarespace.com/static/66e06aecaa21bf3dc7e00155/t/6999e95e34951f1920799696/1771694430352/CONF.+SCHEDULE+2026.pdf | archive-url = https://images.squarespace-cdn.com/content/v1/66e06aecaa21bf3dc7e00155/4a8ff752-50c2-4fc6-a99d-6d9a0c19ddbf/IMG_3971.jpeg | archive-date = 12 May 2026}}</ref>

LSD is a [[biased agonist]] that induces a conformation in serotonin 5-HT<sub>2</sub> receptors that preferentially recruits [[β-arrestin]] over [[Gs alpha subunit|activating G protein]]s.<ref name="Chen_2017">{{cite journal |vauthors=Chen Q, Tesmer JJ |title=A Receptor on Acid |journal=Cell |volume=168 |issue=3 |pages=339–341 |date=January 2017 |doi=10.1016/j.cell.2017.01.012 |pmid=28129534 |pmc=5520807}}</ref> It also has an exceptionally long [[residence time#Pharmacology|residence time]] when bound to serotonin receptors lasting hours, consistent with the long-lasting effects of LSD despite its relatively rapid [[clearance (pharmacology)|clearance]].<ref name="RothGumpper2023">{{cite journal | vauthors = Roth BL, Gumpper RH | title = Psychedelics as Transformative Therapeutics | journal = Am J Psychiatry | volume = 180 | issue = 5 | pages = 340–347 | date = May 2023 | pmid = 37122272 | doi = 10.1176/appi.ajp.20230172 | url = https://cdr.lib.unc.edu/downloads/37720q20d| quote = We now have molecular-level details regarding how psychedelic drugs interact with and activate 5-HT2A receptors (39) (Figure 2B). Studies on a related serotonin receptor (5-HT2B) have clarified how LSD can stabilize distinct signaling complexes (40, 41). A key finding of these studies was the discovery that once LSD binds to the 5-HT2A receptor, a lid is formed over the binding pocket, which "traps" LSD for several hours (39, 40) (Figure 2B). These findings imply that at least part of the reason for the long duration of action of drugs like LSD is the trapping of the receptor via conformational changes that occur after drug binding. These studies also showed that this prolonged action of LSD is due in part to a specific residue within the binding pocket, which is found in humans but not in mice or rats (39). This residue (Ser242) also is essential for the high-affinity interactions of LSD, psilocybin, and perhaps other such drugs at the human and nonhuman primate 5-HT2A receptors.}}</ref><ref name="Chen_2017" /><ref name="HigginsMacMillandeLannoy2025">{{cite journal | vauthors = Higgins GA, MacMillan C, de Lannoy I, Tyler C, Slassi M | title = Pharmacological characterisation of psilocybin and 5-MeO-DMT discriminative cues in the rat and their translational value for identifying novel psychedelics | journal = J Psychopharmacol | volume = | issue = | article-number = 2698811251361453 | date = August 2025 | pmid = 40862395 | doi = 10.1177/02698811251361453 | url = | quote = Based on the time-course data, LSD appeared to show the largest disconnect between plasma exposure and generalisation profile. By 8 h post-dosing, plasma LSD levels were undetectable, yet drug lever generalisation levels were at 54%; even at 24 h post-dose, there was some residual (10%) drug lever responding. LSD is recognised to have a long residence time when bound to the 5-HT2A receptor, which, in the human receptor form, is due to a conformational change on binding that traps an LSD molecule within the binding pocket (Gumpper et al., 2025; Kim et al., 2020). A further feature of LSD is a time-dependent change in the pharmacology of its discriminative cue (Marona-Lewica et al., 2005; Marona-Lewica and Nichols, 2007). Thus, a long residence time bound to the 5-HT2A receptor and/or time-dependent changes in its discriminative cue may explain the PK/PD disconnect in rats. Dolder et al. (2015, 2017) have described a similar disconnection in humans where 100 and 200 µg doses of LSD had a plasma half-life of 2.6 h, yet the subjective effects lasted 8–12 h.}}</ref> In rodents, LSD levels are undetectable by 8{{nbsp}}hours post-dosing, yet LSD continues to produce partial interoceptive effects (54% responding) at this time point.<ref name="HigginsMacMillandeLannoy2025" /> A [[crystal structure]] of the serotonin 5-HT<sub>2B</sub> receptor bound to LSD reveals an [[extracellular]] loop that forms a "lid" over the [[diethylamide]] end of the [[binding pocket|binding cavity]] and "traps" LSD in the binding pocket, which explains the slow rate of LSD unbinding from serotonin receptors.<ref name="RothGumpper2023" /><ref name="WackerWang2017">{{cite journal | vauthors = Wacker D, Wang S, McCorvy JD, Betz RM, Venkatakrishnan AJ, Levit A, Lansu K, Schools ZL, Che T, Nichols DE, Shoichet BK, Dror RO, Roth BL | title = Crystal Structure of an LSD-Bound Human Serotonin Receptor | journal = Cell | volume = 168 | issue = 3 | pages = 377–389.e12 | date = January 2017 | pmid = 28129538 | pmc = 5289311 | doi = 10.1016/j.cell.2016.12.033 }}</ref> The related [[lysergamide]] [[lysergic acid amide]] (LSA) that lacks the diethylamide [[moiety (chemistry)|moiety]] is far less [[potency (pharmacology)|potent]] in comparison.<ref name="WackerWang2017" /> Moreover, a specific [[amino acid|residue]] in the binding pocket is partially responsible for the prolonged action of LSD, and this residue is found in the human protein but not in the receptors of rodents.<ref name="RothGumpper2023" />

LSD is an extraordinarily potent [[psychoactive drug]] and is among the most potent psychedelics known in humans.<ref name="Nichols2018a" /><ref name="Nichols2018b" /><ref name="BrimblecombePinder1975" /> The very high potency of LSD in producing psychedelic-like effects is also the case in animals, including rodents and monkeys.<ref name="BrimblecombePinder1975" /><ref name="HalberstadtChathaKlein2020">{{cite journal | vauthors = Halberstadt AL, Chatha M, Klein AK, Wallach J, Brandt SD | title = Correlation between the potency of hallucinogens in the mouse head-twitch response assay and their behavioral and subjective effects in other species | journal = Neuropharmacology | volume = 167 | issue = | article-number = 107933 | date = May 2020 | pmid = 31917152 | pmc = 9191653 | doi = 10.1016/j.neuropharm.2019.107933 | url = http://usdbiology.com/cliff/Courses/Advanced%20Seminars%20in%20Neuroendocrinology/Serotonergic%20Psychedelics%2020/Halberstadt%2020%20Neuropharm%20potency%20of%20hallucinogens%20%20head-twitch.pdf}}</ref> It is unclear why LSD is so potent.<ref name="Nichols2018b" /><ref name="Nichols2004" /><ref name="Nichols2001">{{cite journal | vauthors = [[David E. Nichols|Nichols DE]] | title = LSD and Its Lysergamide Cousins | pages = 80–87 | journal = The Heffter Review of Psychedelic Research | volume = 2 | date = 2001 | publisher = [[Heffter Research Institute]] | issn = 1534-9640 | url = https://www.heffter.org/wp-content/uploads/2020/04/chap6.pdf | quote = Lysergic Acid N, N-diethylamide (LSD) is the most "famous" (notorious?) of the psychedelics. That dubious distinction came about not only because of its effects, but also because of its extremely high potency. The type of effect it produced was not completely unknown, however, because mescaline had been relatively available to interested persons since the late 1920s, and produced a similar mental state. Aldous Huxley's book The Doors of Perception also generated a great deal of interest in mescaline in the 1950s, at least in certain circles, but its low potency (one gram is only 3-4 doses) made it somewhat uneconomical for manufacture. This cost factor may be one of the reasons that it never achieved the popularity gained by LSD in the 1960s and 1970s. By contrast, LSD was easily made from relatively available starting materials such as ergotamine, and its high potency made it economical to manufacture in relatively large quantities. One gram of LSD probably costs no more than a few hundred dollars in raw materials to manufacture, whereas it represents approximately 10,000 clinical doses that could "retail" on the street for upwards of $50,000. Combine this strong economic incentive with the high potency of the drug, which makes distribution easy because doses are very small and easily hidden, and one readily sees some of the factors that led to the high popularity of LSD. [...]Indeed, the potency of LSD at the 5-HT2A receptor is not as great as that of some of the amphetamine hallucinogens such as DOB or DOI, yet its human potency is about ten times greater. [...] Furthermore, there is a cavity within these receptors that accommodates and is complementary to the activating drug, in this case LSD. What we are forced to conclude is that the area within the receptor that binds to the diethylamide function of LSD is a specific region that must be just large enough to contain the diethyl groups. [...]}}</ref> The affinity and [[receptor activation|activational]] potency of LSD at the human serotonin 5-HT<sub>2A</sub> receptor ''[[in vitro]]'' is unremarkable compared to other psychedelics such as [[DOI (drug)|DOI]] and [[DOB (drug)|DOB]].<ref name="Nichols2018b" /><ref name="Nichols2004" /><ref name="Nichols2001" /> There is no evidence for its greater potency being related to [[pharmacokinetics]] or [[drug metabolism|metabolism]].<ref name="Nichols2004" /> It appears that the ''N'',''N''-diethylamide [[moiety (chemistry)|moiety]] of LSD fits into a sterically constrained region of the serotonin 5-HT<sub>2A</sub> receptor that specifically accommodates this moiety.<ref name="Nichols2018b" /><ref name="GumpperNichols2024" /><ref name="Nichols2001" />

LSD, like other psychedelics, has been found to increase the [[gene expression|expression]] of [[gene]]s related to [[synaptic plasticity]] and hence to have [[psychoplastogen]]ic effects.<ref name="CalderHasler2023">{{cite journal | vauthors = Calder AE, Hasler G | title = Towards an understanding of psychedelic-induced neuroplasticity | journal = Neuropsychopharmacology | volume = 48 | issue = 1 | pages = 104–112 | date = January 2023 | pmid = 36123427 | pmc = 9700802 | doi = 10.1038/s41386-022-01389-z }}</ref> This appears to be mediated by serotonin 5-HT<sub>2A</sub> receptor agonism.<ref name="CalderHasler2023" /> LSD has also been reported to act as a highly [[potency (pharmacology)|potent]] [[positive allosteric modulator]] of the [[tropomyosin receptor kinase B]] (TrkB), one of the [[receptor (biochemistry)|receptor]]s of [[brain-derived neurotrophic factor]] (BDNF).<ref name="HatzipantelisOlson2024">{{cite journal | vauthors = Hatzipantelis CJ, Olson DE | title = The Effects of Psychedelics on Neuronal Physiology | journal = Annu Rev Physiol | volume = 86 | issue = | pages = 27–47 | date = February 2024 | pmid = 37931171 | doi = 10.1146/annurev-physiol-042022-020923 | pmc = 10922499 | url = }}</ref><ref name="MolinerGirychBrunello2023">{{cite journal | vauthors = Moliner R, Girych M, Brunello CA, Kovaleva V, Biojone C, Enkavi G, Antenucci L, Kot EF, Goncharuk SA, Kaurinkoski K, Kuutti M, Fred SM, Elsilä LV, Sakson S, Cannarozzo C, Diniz CR, Seiffert N, Rubiolo A, Haapaniemi H, Meshi E, Nagaeva E, Öhman T, Róg T, Kankuri E, Vilar M, Varjosalo M, Korpi ER, Permi P, Mineev KS, Saarma M, Vattulainen I, Casarotto PC, Castrén E | title = Psychedelics promote plasticity by directly binding to BDNF receptor TrkB | journal = Nat Neurosci | volume = 26 | issue = 6 | pages = 1032–1041 | date = June 2023 | pmid = 37280397 | pmc = 10244169 | doi = 10.1038/s41593-023-01316-5 | url = }}</ref> However, subsequent studies failed to reproduce these findings and instead found no interaction of LSD with TrkB.<ref name="JainGumpperSlocum2025">{{cite journal | vauthors = Jain MK, Gumpper RH, Slocum ST, Schmitz GP, Madsen JS, Tummino TA, Suomivuori CM, Huang XP, Shub L, DiBerto JF, Kim K, DeLeon C, Krumm BE, Fay JF, Keiser M, Hauser AS, Dror RO, Shoichet B, Gloriam DE, Nichols DE, Roth BL | title = The polypharmacology of psychedelics reveals multiple targets for potential therapeutics | journal = Neuron | volume = 113| issue = 19| pages = 3129–3142.e9| date = July 2025 | pmid = 40683247 | doi = 10.1016/j.neuron.2025.06.012 | url = https://www.cell.com/cms/10.1016/j.neuron.2025.06.012/attachment/7d8365fe-51f3-4a28-bf40-9999bec837f6/mmc11.pdf | quote = Recent studies have suggested that psychedelics such as LSD directly interact with TrkB with high affinity, promoting BDNF-mediated neuroplasticity and antidepressant-like effects via allosteric potentiation of BDNF signaling in active synapses.8 To investigate this, we screened LSD across 450 human kinases, including TrkB, but found no significant interactions between LSD and any tested human kinases. Further experiments in transfected cells revealed no effect of LSD or psilocin on BDNF-mediated activation of a TrkB reporter. We note that similar negative preliminary results, which have not yet been published in a peer-reviewed journal, were recently reported by Boltaev et al.63}}</ref>

There appears to be no significant acute [[drug tolerance|tolerance]] to the subjective effects of LSD.<ref name="Nichols2018a" /><ref name="Liechti2016">{{citation | author = Matthias Liechti | title = Pharmacology of novel psychoactive substances, MDMA, and LSD | work = Department of Biomedicine. Report 2014–2016 | pages=52–53 | date=2016 | url = https://biomedizin.unibas.ch/fileadmin/user_upload/biomedizin/research/fg_liechti_psychopharmacology_research/DBM_Report_2014-2016_liechti.pdf | quote = LSD produced subjective drug effects that lasted up to 12 h (Fig. 3a) and correlated well with the concentrations of LSD in the blood plasma over time (Fig. 3b and c). The half-life of LSD in plasma was 3.5 h. In contrast to LSD, the half-life of MDMA is longer (8 h), but the effects of MDMA last only up to 6 h despite the continued presence of the substance in the body (Fig. 3d). Thus, there is marked acute tolerance to the effects of MDMA. [...] Fig. 3: Pharmacokinetics-Pharmacodynamics of LSD. LSD effects last up to 12 h (a), corresponding to its plasma-concentration time curve (b) and exhibiting no hysteresis in the LSD concentration-effect plot (c). In contrast, the MDMA concentration-effect plot shows pronounced hysteresis consistent with acute tolerance (d).}}</ref> Hence, its [[duration of action|duration]] appears to be dictated by [[pharmacokinetics]] rather than by [[pharmacodynamics]].<ref name="Nichols2018a" /><ref name="Liechti2016" /> This is in contrast to [[MDMA]], which shows marked acute tolerance and a duration of effects that is shorter than its [[elimination half-life]].<ref name="Liechti2016" />

The [[cryo-EM]] [[protein–ligand complex|structure]]s of the serotonin 5-HT<sub>2A</sub> receptor with LSD, as well as with various other psychedelics and serotonin 5-HT<sub>2A</sub> receptor agonists, have been solved and published by [[Bryan L. Roth]] and colleagues.<ref name="GumpperJainKim2025">{{cite journal | vauthors = Gumpper RH, Jain MK, Kim K, Sun R, Sun N, Xu Z, DiBerto JF, Krumm BE, Kapolka NJ, Kaniskan HÜ, Nichols DE, Jin J, Fay JF, Roth BL | title = The structural diversity of psychedelic drug actions revealed | journal = Nature Communications | volume = 16 | issue = 1 | article-number = 2734 | date = March 2025 | pmid = 40108183 | doi = 10.1038/s41467-025-57956-7 | pmc = 11923220 | bibcode = 2025NatCo..16.2734G }}</ref><ref name="GumpperDiBertoJain2022">{{cite conference | vauthors = Gumpper RH, DiBerto J, Jain M, Kim K, Fay J, Roth BL | title = Structures of Hallucinogenic and Non-Hallucinogenic Analogues of the 5-HT2A Receptor Reveals Molecular Insights into Signaling Bias | conference = University of North Carolina at Chapel Hill Department of Pharmacology Research Retreat September 16th, 2022 – William and Ida Friday Center | date = September 2022 | url = https://www.med.unc.edu/pharm/wp-content/uploads/sites/930/2022/07/COMPLETE-PHARM-RETREAT-PROGRAM-2022-UPDATE.pdf#page=37}}</ref>

====Mechanisms of action====
{{Multiple image
| align = left
| total_width = 500
| image1 = FMRI V1 RSFC LSD.png
| class1 = skin-invert-image
| caption1 = [[Resting state fMRI]] [[BOLD-contrast imaging]] shows increased [[primary visual cortex]] (V1) [[cerebral blood flow]] (CBF) and increased V1 [[resting state functional connectivity]] (RSFC), which correlated more strongly with the visual hallucinatory aspect of the LSD experience. Increased V1 RSFC also correlated with [[visual analogue scale]] (VAS) ratings of simple hallucinations and the magnitude of CBF observed in the visual cortex correlated positively with ratings of complex imagery on the LSD-induced [[altered state of consciousness]] (ASC).<ref name="pmid27071089">{{cite journal |vauthors=Carhart-Harris RL, Muthukumaraswamy S, Roseman L, Kaelen M, Droog W, Murphy K, Tagliazucchi E, Schenberg EE, Nest T, Orban C, Leech R, Williams LT, Williams TM, Bolstridge M, Sessa B, McGonigle J, Sereno MI, Nichols D, Hellyer PJ, Hobden P, Evans J, Singh KD, Wise RG, Curran HV, Feilding A, Nutt DJ |title=Neural correlates of the LSD experience revealed by multimodal neuroimaging |journal=[[Proceedings of the National Academy of Sciences of the United States of America]] |volume=113 |issue=17 |pages=4853–4858 |date=11 April 2016 |pmid=27071089 |pmc=4855588 |doi=10.1073/pnas.1518377113 |bibcode=2016PNAS..113.4853C |doi-access=free}}</ref>
| width1 = 
| height1 = 
| image2 = FMRI PH RSFC LSD.png
| class2 = skin-invert-image
| caption2 = [[Resting state fMRI]] [[BOLD-contrast imaging]] shows decreased [[Parahippocampal gyrus|bilateral parahippocampal]] (PH) [[resting state functional connectivity]] (RSFC), which correlated with the [[ego-dissolution]] aspect of the LSD experience. A significant relationship was also found between decreased [[posterior cingulate cortex]] (PCC) [[Alpha wave|alpha power]] and [[default mode network]] (DMN) disintegration with ego-dissolution.<ref name="pmid27071089" />
| width2 = 
| height2 = 
| footer = 
}}

Neuroimaging studies using [[resting state]] [[fMRI]] recently suggested that LSD changes the cortical functional architecture.<ref name="Singleton SP">{{cite journal | vauthors = Singleton SP, Luppi AI, Carhart-Harris RL, Cruzat J, Roseman L, Nutt DJ, Deco G, Kringelbach ML, Stamatakis EA, Kuceyeski A |title = Receptor-informed network control theory links LSD and psilocybin to a flattening of the brain's control energy landscape|journal = Nat Commun |volume=13 | issue=1 | article-number=5812 | date=Oct 2022 | pmid=36192411 | doi = 10.1038/s41467-022-33578-1 | pmc=9530221 | bibcode=2022NatCo..13.5812S | doi-access=free }}</ref> These modifications spatially overlap with the distribution of serotonergic receptors. In particular, increased connectivity and activity were observed in regions with high expression of [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]], while a decrease in activity and connectivity was observed in cortical areas that are dense with [[5-HT1A receptor|5-HT<sub>1A</sub> receptor]].<ref name="Delli Pizzi S BP:CNNI">{{cite journal |vauthors=Delli Pizzi S, Chiacchiaretta P, Sestieri C, Ferretti A, Onofrj M, Della Penna S, Roseman L, Timmermann C, Nutt DJ, Carhart-Harris RL, Sensi SL |title=Spatial Correspondence of LSD-Induced Variations on Brain Functioning at Rest With Serotonin Receptor Expression |journal=Biol Psychiatry Cogn Neurosci Neuroimaging |volume=8 |issue=7 |pages=768–776 |date=July 2023 |pmid=37003409 |doi=10.1016/j.bpsc.2023.03.009 |s2cid=257862535}}</ref> Experimental data suggest that subcortical structures, particularly the thalamus, play a synergistic role with the cerebral cortex in mediating the psychedelic experience. LSD, through its binding to cortical 5-HT<sub>2A</sub> receptors, may enhance excitatory neurotransmission along frontostriatal projections and, consequently, reduce thalamic filtering of sensory stimuli towards the cortex.<ref name="Delli Pizzi S NeuroImage">{{cite journal |vauthors=Delli Pizzi S, Chiacchiaretta P, Sestieri C, Ferretti A, Tullo MG, Della Penna S, Martinotti G, Onofrj M, Roseman L, Timmermann C, Nutt DJ, Carhart-Harris RL, Sensi SL |title=LSD-induced changes in the functional connectivity of distinct thalamic nuclei |journal=NeuroImage |volume=283 |article-number=120414 |date=Dec 2023 |pmid=37858906 |doi=10.1016/j.neuroimage.2023.120414 |doi-access=free}}</ref> This phenomenon appears to involve ventral, intralaminar, and pulvinar nuclei selectively.<ref name="Delli Pizzi S NeuroImage"/>

====Neurotoxicity====
{{See also|Psychedelic microdosing#Neurological toxicity|Psychedelic drug#Neurotoxicity}}

Chronic administration of LSD has been associated with long-lasting [[schizophrenia]]-like behavioral changes in rodents, which were not blocked by serotonin 5-HT<sub>2A</sub> receptor antagonism but may instead be related to LSD's [[dopamine]] [[D2-like receptor|D<sub>2</sub>-like receptor]] agonism.<ref name="Nichols2016" /><ref name="KuypersNgErritzoe2019" /><ref name="KyzarNicholsGainetdinov2017">{{cite journal | vauthors = Kyzar EJ, Nichols CD, Gainetdinov RR, Nichols DE, Kalueff AV | title = Psychedelic Drugs in Biomedicine | journal = Trends Pharmacol Sci | volume = 38 | issue = 11 | pages = 992–1005 | date = November 2017 | pmid = 28947075 | doi = 10.1016/j.tips.2017.08.003 | url = }}</ref><ref name="Marona-LewickaNicholsNichols2011">{{cite journal | vauthors = Marona-Lewicka D, Nichols CD, Nichols DE | title = An animal model of schizophrenia based on chronic LSD administration: old idea, new results | journal = Neuropharmacology | volume = 61 | issue = 3 | pages = 503–512 | date = September 2011 | pmid = 21352832 | pmc = 3110609 | doi = 10.1016/j.neuropharm.2011.02.006 | url = }}</ref> Single macrodoses of LSD do not produce such changes in rodents, but the preceding findings may have implications for continuous [[psychedelic microdosing]] with LSD.<ref name="NicholsNichols2021">{{cite book | vauthors = Nichols DE, Nichols CD | chapter=The Pharmacology of Psychedelics | veditors = Grob CS, Grigsby J | title=Handbook of Medical Hallucinogens | publisher=Guilford Publications | year=2021 | isbn=978-1-4625-4544-5 | chapter-url=https://books.google.com/books?id=ebb2DwAAQBAJ&pg=PA3 | access-date=17 January 2025 | pages=3–28}}</ref><ref name="KuypersNgErritzoe2019" />

LSD, via activation of serotonin 5-HT<sub>2</sub> receptors, has been found to potentiate [[MDMA]]-induced [[serotonergic neurotoxicity]] in rodents.<ref name="VirmaniAliBinienda2010">{{cite journal | vauthors = Virmani A, Ali SF, Binienda ZK | title = Neuroprotective strategies in drug abuse-evoked encephalopathy | journal = Annals of the New York Academy of Sciences | volume = 1199 | issue =  1| pages = 52–68 | date = June 2010 | pmid = 20633109 | doi = 10.1111/j.1749-6632.2009.05171.x | bibcode = 2010NYASA1199...52V | quote = LSD has been reported to potentiate the neurotoxic action of MDMA in animal experiments.85 In these experiments, the MDMA-induced neurotoxicity was dose dependently increased by LSD and attenuated by 5-HT2A/2C receptor antagonist MDL 11,939. }}</ref><ref name="HirschfeldSmit-RigtervanderGouwe2021">{{cite journal | vauthors = Hirschfeld T, Smit-Rigter L, van der Gouwe D, Reiche S, Stöver H, Majić T | title=Safer Tripping: Serotonergic Psychedelics and Drug Checking. Submission and Detection Rates, Potential Harms, and Challenges for Drug Analysis | journal=Current Addiction Reports | volume=8 | issue=3 | date=2021 | issn=2196-2952 | doi=10.1007/s40429-021-00385-5 | pages=389–398 | url=https://link.springer.com/10.1007/s40429-021-00385-5 | access-date=6 January 2026 | quote=Also, the concomitant use of other substance classes, either intentionally or unintentionally due to adulterations, could be a health risk since LSD has been shown to potentiate the neurotoxic effect of MDMA in animals [85].}}</ref><ref name="ArmstrongPaikChhith2004">{{cite journal | vauthors = Armstrong BD, Paik E, Chhith S, Lelievre V, Waschek JA, Howard SG | title = Potentiation of (DL)-3,4-methylenedioxymethamphetamine (MDMA)-induced toxicity by the serotonin 2A receptior partial agonist d-lysergic acid diethylamide (LSD), and the protection of same by the serotonin 2A/2C receptor antagonist MDL 11,939 | journal = Neuroscience Research Communications | volume = 35 | issue = 2 | pages = 83–95 | date = 2004 | doi = 10.1002/nrc.20023 }}</ref>

===Pharmacokinetics===
====Absorption====
The oral [[Bioavailability (medicine)|bioavailability]] of LSD was crudely estimated as approximately 71% using previous data on [[intravenous]] administration of LSD.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" /> The sample was equally divided between male and female subjects. There were no significant sex differences observed in the pharmacokinetics of LSD.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" /> In a subsequent higher-quality 2025 study, the oral bioavailability of LSD was about 80%.<ref name="ZhangLinWang2026" /><ref name="ArikciHolzeMueller2025" /><ref name="Holze_2024">{{cite journal | vauthors = Holze F, Mueller L, Vizeli P, Luethi D, Rudin D, Hysek C, Liechti M, Arikci D | title = Oral LSD base and tartrate bioequivalence and absolute bioavailability in healthy participants | journal = Neuroscience Applied | volume = 3 | article-number = 105132 | date = 2024 | doi = 10.1016/j.nsa.2024.105132 | doi-access = free }}</ref>

The [[pharmacokinetics]] of LSD were not properly determined until 2015, which is not surprising for a drug with the kind of low-μg potency that LSD possesses.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" /> In a sample of 16 healthy subjects, a single mid-range 200{{nbsp}}μg oral dose of LSD was found to produce mean [[Cmax (pharmacology)|maximal concentration]]s of 4.5{{nbsp}}ng/mL at a median of 1.5{{nbsp}}hours (range 0.5–4{{nbsp}}hours) post-administration.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" />

A large meal before taking LSD has been found to result in circulating levels that were 50% lower than on an empty stomach.<ref name="PassieHalpernStrichtenoth2008" />

====Distribution====
In terms of [[distribution (pharmacology)|distribution]], it is estimated that only about 1 to 1.5% of the drug reaches the brain both in animals and humans.<ref name="BrimblecombePinder1975" /> Following a typical 100{{nbsp}}μg dose in humans, this would be about 1{{nbsp}}μg that is distributed into the brain.<ref name="BrimblecombePinder1975" /> LSD levels in different brain areas have been found to vary in monkeys.<ref name="BrimblecombePinder1975" /><ref name="SnyderReivich1966">{{cite journal | vauthors = Snyder SH, Reivich M | title = Regional localization of lysergic acid diethylamide in monkey brain | journal = Nature | volume = 209 | issue = 5028 | pages = 1093–1095 | date = March 1966 | pmid = 4958949 | doi = 10.1038/2091093a0 | bibcode = 1966Natur.209.1093S | url = https://www.researchgate.net/publication/18209711}}</ref> Levels were equal in blood, [[cerebral cortex]], [[cerebellum]], and [[brainstem]], whereas levels were 1.5{{nbsp}}times higher in the [[thalamus]] and [[extrapyramidal system]], 2 to 3{{nbsp}}times higher in the [[hypothalamus]] and [[limbic system]], 2 to 5{{nbsp}}times higher in the [[auditory cortex|auditory]] and [[visual cortex]], 5 to 7{{nbsp}}times higher in the [[posterior pituitary]] and [[pineal gland]], and 10{{nbsp}}times higher in the [[anterior pituitary gland]].<ref name="BrimblecombePinder1975" /><ref name="SnyderReivich1966" /> These varying concentrations in different brain areas may explain the profile of psychedelic effects of LSD.<ref name="BrimblecombePinder1975" /><ref name="SnyderReivich1966" /> Bodily distribution of LSD has also been studied.<ref name="Herian2022">{{cite book | vauthors = Herian M | title=Handbook of Substance Misuse and Addictions | chapter=Pharmacological Action of LSD: LSD Effect on the Neurotransmission and Animal Behavior | publisher=Springer International Publishing | publication-place=Cham | date=2022 | isbn=978-3-030-92391-4 | doi=10.1007/978-3-030-92392-1_131 | chapter-url=https://link.springer.com/10.1007/978-3-030-92392-1_131 | access-date=7 June 2025 | pages=2457–2475}}</ref><ref name="PassieHalpernStrichtenoth2008" />

It has been said that there is a peculiar 40-minute lag before [[onset of action|onset]] of the psychedelic effects of LSD when it is administered [[intravenous injection|intravenously]].<ref name="GumpperNichols2024" /> This has been said to be related to time-dependent interactions of LSD with the serotonin 5-HT<sub>2A</sub> receptor.<ref name="GumpperNichols2024" /> However, contradicting the preceding claims, other sources have stated that intravenous injection of LSD results in onset of effects within a few minutes.<ref name="PassieHalpernStrichtenoth2008" /><ref name="Shulgin1980b">{{cite journal | vauthors = Shulgin AT | title = Profiles of Psychedelic Drugs: LSD | journal = J Psychedelic Drugs | volume = 12 | issue = 2 | pages = 173–174 | date = 1980 | pmid = 7420434 | doi = 10.1080/02791072.1980.10471571 | url = }}</ref><ref name="BrimblecombePinder1975" /> In a 2025 pharmacokinetic study comparing oral and intravenous LSD, the onset orally was about 45{{nbsp}}minutes and the onset by intravenous injection was about 2.5{{nbsp}}minutes.<ref name="ArikciHolzeMueller2025" /> In addition, [[intrathecal injection]] (intraspinal injection) is reported to have a virtually instantaneous onset of action.<ref name="PassieHalpernStrichtenoth2008" /><ref name="Shulgin1980b" /> However, in the 2025 study, time to maximal effects was about 2.5{{nbsp}}hours orally and about 1.2{{nbsp}}hours intravenously.<ref name="ArikciHolzeMueller2025" /> In an earlier 2016 study, intravenous LSD effects similarly peaked after about 1.7{{nbsp}}hours.<ref name="Nichols2016" /><ref name="Carhart-HarrisMuthukumaraswamyRoseman2016">{{cite journal | vauthors = Carhart-Harris RL, Muthukumaraswamy S, Roseman L, Kaelen M, Droog W, Murphy K, Tagliazucchi E, Schenberg EE, Nest T, Orban C, Leech R, Williams LT, Williams TM, Bolstridge M, Sessa B, McGonigle J, Sereno MI, Nichols D, Hellyer PJ, Hobden P, Evans J, Singh KD, Wise RG, Curran HV, Feilding A, Nutt DJ | title = Neural correlates of the LSD experience revealed by multimodal neuroimaging | journal = Proc Natl Acad Sci U S A | volume = 113 | issue = 17 | pages = 4853–8 | date = April 2016 | pmid = 27071089 | pmc = 4855588 | doi = 10.1073/pnas.1518377113 | doi-access = free | bibcode = 2016PNAS..113.4853C | url = https://www.carhartharrislab.com/s/LSD_PNAS_paper_2016.pdf}}</ref> For comparison, intravenous [[dimethyltryptamine]] (DMT) given as a [[bolus (medicine)|bolus]] has been found to produce maximal effects after about 2{{nbsp}}minutes and intravenous psilocybin given over 60{{nbsp}}seconds after about 4{{nbsp}}minutes.<ref name="HolzeSinghLiechti2024" /><ref name="Nichols2016" /> Doses of LSD are said to be similar by oral and injectable routes, with the exception of intrathecal injection in which the dose is reduced to about one-third of usual.<ref name="Shulgin1980b" />

====Metabolism====
[[File:Metabolism of LSD in animals and humans.png|thumb|right|300px|class=skin-invert-image|[[Drug metabolism|Metabolism]] of LSD in animals and humans.<ref name="Dolder2017">{{cite thesis | vauthors = Dolder P | title=The Pharmacology of d-Lysergic Acid Diethylamide (LSD) | date=2017 | publisher=University of Basel | doi=10.5451/UNIBAS-006786123 | url=https://core.ac.uk/download/pdf/154350706.pdf#page=112 | access-date=3 June 2025 | page=112}}</ref><ref name="LibânioOsórioMarta2019">{{cite journal | vauthors = Libânio Osório Marta RF | title = Metabolism of lysergic acid diethylamide (LSD): an update | journal = Drug Metab Rev | volume = 51 | issue = 3 | pages = 378–387 | date = August 2019 | pmid = 31266388 | doi = 10.1080/03602532.2019.1638931 | url = }}</ref><ref name="PassieHalpernStrichtenoth2008" />]]

The [[metabolite]]s of LSD include [[2-oxo-3-hydroxy-LSD]] (O-H-LSD), [[2-oxo-LSD]], [[lysergic acid ethylamide]] (LAE), [[lysergic acid ethyl-2-hydroxyethylamide]] (LEO), [[nor-LSD]], [[13-hydroxy-LSD]], [[14-hydroxy-LSD]], and the [[glucuronide]] [[conjugate (biochemistry)|conjugate]]s of the 13- and 14-hydroxylated metabolites, among other possible metabolites.<ref name="Dolder2017" /><ref name="DolderSchmidHaschke2015" /><ref name="MeyerMaurer2011" /><ref name="MeyerMaurer2012">{{cite book | vauthors = Maurer HH, Meyer MR | chapter = Drugs of Abuse (Including Designer Drugs) | title = Metabolism of Drugs and Other Xenobiotics | pages = 429–463 | date = 18 April 2012 | doi = 10.1002/9783527630905.ch16 | publisher = Wiley | isbn = 978-3-527-32903-8 | url = https://onlinelibrary.wiley.com/doi/10.1002/9783527630905.ch16 | access-date = 7 June 2025 | quote = [LSD] is metabolized to the following five metabolites: N-demethyl-LSD (nor-LSD), 2-oxo-LSD, 2-oxo-3-hydroxy-LSD, 13-hydroxy-LSD, and 14-hydroxy-LSD [72–74]. The 13- and 14-hydroxy metabolites are additionally excreted as glucuronides [74]. 2-Oxo-3-hydroxy-LSD was shown to be the main human urinary metabolite with concentrations 4–40 times higher than that of LSD [73–75]. In incubations of LSD with human liver microsomes and hepatocytes, 2,3-dihydroxy-LSD could be identified [71]. So far, the contribution and importance of specific enzymes in the formation of the LSD main metabolites, such as 2-oxo-3-hydroxy-LSD, remain unclear. }}</ref> The major metabolite of LSD is O-H-LSD.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" /> Levels of O-H-LSD in [[urine]] have been found to be 4 to 40{{nbsp}}times higher than those of LSD, indicating extensive [[drug metabolism|metabolism]] of LSD into this compound.<ref name="MeyerMaurer2011" /><ref name="MeyerMaurer2012" /> It is formed by [[cytochrome P450]] [[enzyme]]s, although the specific enzymes involved are unknown, and O-H-LSD's potential [[pharmacology]] is little-studied.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" /> However, it was found to have profoundly reduced activity at the [[serotonin]] [[5-HT2 receptor|5-HT<sub>2</sub> receptor]]s relative to LSD ''[[in vitro]]''.<ref name="LuethiHoenerKrähenbühl2019">{{cite journal | vauthors = Luethi D, Hoener MC, Krähenbühl S, Liechti ME, Duthaler U | title = Cytochrome P450 enzymes contribute to the metabolism of LSD to nor-LSD and 2-oxo-3-hydroxy-LSD: Implications for clinical LSD use | journal = Biochem Pharmacol | volume = 164 | issue = | pages = 129–138 | date = June 2019 | pmid = 30981875 | doi = 10.1016/j.bcp.2019.04.013 | url = }}</ref> Little is known about the specific enzymes responsible for the formation of LSD metabolites.<ref name="MeyerMaurer2011">{{cite journal | vauthors = Meyer MR, Maurer HH | title = Absorption, distribution, metabolism and excretion pharmacogenomics of drugs of abuse | journal = Pharmacogenomics | volume = 12 | issue = 2 | pages = 215–233 | date = February 2011 | pmid = 21332315 | doi = 10.2217/pgs.10.171 | url = | quote = It is rapidly metabolized to the following five metabolites which have been identified in urine or blood from human users: N-demethyl-LSD (nor-LSD), 2-oxoLSD, 2-oxo-3-hydroxy-LSD, 13-hydroxyLSD and 14-hydroxy-LSD [187–189]. The 13- and 14-hydroxy metabolites are additionally excreted as glucuronides [188]. [...] 2-oxo-3-hydroxy-LSD was shown to be the main human urinary metabolite with concentrations four- to 40-times higher than that of LSD [187,188,191]. As concluded by Yu in his review on indolalkylamines, almost nothing is known regarding the contribution of specific drug-metabolizing enzymes to the production of individual LSD metabolites in humans.}}</ref><ref name="MeyerMaurer2012"/> LSD is not metabolized by [[monoamine oxidase]] (MAO) enzymes.<ref name="RachedCampanaFiani2026">{{cite journal | vauthors = Rached G, Campana A, Fiani D, Nguyen C, Van den Eynde V, Gillman PK, Barnett BS | title = Safety and Efficacy of Monoamine Oxidase Inhibitors in Patients Who Use Psychoactive Substances: Potential Drug Interactions and Substance Use Disorder Treatment Data | journal = CNS Drugs | volume = 40| issue = 3| pages = 359–417| date = January 2026 | pmid = 41546846 | doi = 10.1007/s40263-025-01256-7 | url = }}</ref>

====Elimination====
Only 1% of the drug was eliminated in [[urine]] unchanged, whereas 13% was eliminated as O-H-LSD within 24{{nbsp}}hours.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" />

Aghajanian and Bing (1964) found LSD had an elimination half-life of only 175{{nbsp}}minutes (about 3{{nbsp}}hours);<ref name="Aghajanian">{{cite journal |vauthors=Aghajanian GK, Bing OH |title=Persistence of lysergic acid diethylamide in the plasma of human subjects |journal=Clinical Pharmacology and Therapeutics |volume=5 |issue=5 |pages=611–614 |year=1964 |pmid=14209776 |doi=10.1002/cpt196455611| url=http://www.maps.org/w3pb/new/1964/1964_aghajanian_2224_1.pdf |s2cid=29438767 |archive-url= https://web.archive.org/web/20090327144227/http://www.maps.org/w3pb/new/1964/1964_aghajanian_2224_1.pdf |archive-date=March 27, 2009}}</ref> however, using more accurate techniques, Papac and Foltz (1990) reported that 1{{nbsp}}μg/kg oral LSD given to a single male volunteer had an apparent plasma half-life of 5.1{{nbsp}}hours, with a peak plasma concentration of 5{{nbsp}}ng/mL at 3{{nbsp}}hours post-dose.<ref name="Papac">{{cite journal |vauthors=Papac DI, Foltz RL |title=Measurement of lysergic acid diethylamide (LSD) in human plasma by gas chromatography/negative ion chemical ionization mass spectrometry |journal=Journal of Analytical Toxicology |volume=14 |issue=3 |pages=189–190 |date=May–June 1990 |pmid=2374410 |doi=10.1093/jat/14.3.189 |url=http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=6265&DocPartID=6624 |url-status=live|format=PDF |archive-date=April 29, 2011|archive-url=https://web.archive.org/web/20110429060433/http://www.erowid.org/references/refs_view.php?A=ShowDocPartFrame&C=ref&ID=6265&DocPartID=6624}}</ref> In a more modern 2015 study, concentrations of LSD decreased following [[first-order kinetics]] with a [[half-life]] of 3.6 ± 0.9 hours and a [[terminal half-life]] of 8.9 ± 5.9 hours.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" /> A 2026 review found half-lives ranging from 3.0 to 4.3{{nbsp}}hours in different studies.<ref name="ZhangLinWang2026" />

====Miscellaneous====
The acute effects of LSD normally last between 6 and 12{{nbsp}}hours depending on dose, tolerance, and age.<ref name="TiHKAL">{{cite book | author1 = [[Alexander T. Shulgin]] | author2 = [[Ann Shulgin]] | chapter = #26. LSD-25 Acid; Lysergide; D-Lysergic Acid Diethylamide; Meth-LAD; D-Lysergamide, N,N-Diethyl; N,N-Diethyl-D-Lysergamide; 9,10-Didehydro-N,N-Diethyl-6-Methylergoline-8b-Carboxamide | pages = 490–499 | chapter-url = https://www.erowid.org/library/books_online/tihkal/tihkal26.shtml | title = [[TiHKAL: The Continuation]] | publisher = Transform Press | date = 1997 | edition = 1st | location = Berkeley, CA | isbn = 978-0-9630096-9-2 | oclc = 38503252}}</ref><ref name="PassieHalpernStrichtenoth2008" /> In a modern study, the effects of the dose of LSD given lasted for up to 12{{nbsp}}hours and were closely correlated with the concentrations of LSD present in circulation over time, with no acute [[drug tolerance|tolerance]] observed.<ref name="DolderSchmidHaschke2015" /><ref name="Muc2016" />

==Chemistry==
[[File:Lysergide stereoisomers structural formulae v.2.png|class=skin-invert-image|thumb|upright=1.35|The four possible stereoisomers of the LSD molecule. Only LSD (''d''-LSD) is active. The other, inactive isomers are [[iso-LSD]] (''d''-iso-LSD), [[l-LSD|''l''-LSD]], and [[l-iso-LSD|''l''-iso-LSD]].]]

LSD is a [[chirality (chemistry)|chiral]] compound with two [[stereocenter]]s at the [[carbon]] atoms C-5 and C-8, so that theoretically four different [[optical isomerism|optical isomers]] of LSD could exist. LSD, also called ''d''-LSD or (+)-LSD,<ref>{{Cite book |title=Handbook of Medical Hallucinogens |date=2021 |publisher=Guilford Publications |isbn=978-1-4625-4545-2 |page=160 |language=en |chapter=LSD |chapter-url=https://mcb.berkeley.edu/labs2/presti/sites/mcb.berkeley.edu.labs2.presti/files/u3/2021%20LSD%20Chapter%20Panik%20Presti.pdf |access-date=March 14, 2024 |archive-date=March 14, 2024 |archive-url=https://web.archive.org/web/20240314163910/https://mcb.berkeley.edu/labs2/presti/sites/mcb.berkeley.edu.labs2.presti/files/u3/2021%20LSD%20Chapter%20Panik%20Presti.pdf |url-status=live }}</ref> has the [[absolute configuration]] (5''R'',8''R''). The other stereoisomers are [[iso-LSD]] (''d''-iso-LSD), [[l-LSD|''l''-LSD]], and [[l-iso-LSD|''l''-iso-LSD]].

The 5''S''- or ''levo''- stereoisomers of lysergamides do not exist in nature and are not formed during the synthesis from [[Descriptor (chemistry)#dl|''d'']]-lysergic acid. [[Retrosynthesis|Retrosynthetically]], the C-5 stereocenter could be analysed as having the same configuration as the alpha carbon of the naturally occurring amino acid L-[[tryptophan]], the precursor to all biosynthetic ergoline compounds.

However, LSD and iso-LSD, the two C-8 isomers, rapidly interconvert in the presence of [[base (chemistry)|bases]], as the alpha proton is acidic and can be [[deprotonated]] and reprotonated. Non-psychoactive iso-LSD, which has formed during the synthesis, can be separated by [[chromatography]] and can be isomerized to LSD.

Pure salts of LSD are [[triboluminescent]], emitting small flashes of white light when shaken in the dark.<ref name="TiHKAL" /> LSD is strongly [[fluorescent]] and will glow bluish-white under [[UV light]].

===Synthesis===
The [[chemical synthesis]] of LSD has been described.<ref name="Nichols2018a" /><ref name="TiHKAL" /> It is commonly synthesized by reacting [[diethylamine]] with an activated form of [[lysergic acid]]. Activating reagents include [[phosphoryl chloride]]<ref name="synth1">{{cite journal |vauthors=Monte AP, Marona-Lewicka D, Kanthasamy A, Sanders-Bush E, Nichols DE |date=March 1995 |title=Stereoselective LSD-like activity in a series of d-lysergic acid amides of (R)- and (S)-2-aminoalkanes |journal=Journal of Medicinal Chemistry |volume=38 |issue=6 |pages=958–66 |pmid=7699712 |doi=10.1021/jm00006a015}}</ref> and [[peptide coupling reagent]]s.<ref name="synth2">{{cite journal |vauthors=Nichols DE, Frescas S, Marona-Lewicka D, Kurrasch-Orbaugh DM |date=September 2002 |title=Lysergamides of isomeric 2,4-dimethylazetidines map the binding orientation of the diethylamide moiety in the potent hallucinogenic agent N, N-diethyllysergamide (LSD) |journal=Journal of Medicinal Chemistry |volume=45 |issue=19 |pages=4344–9 |pmid=12213075 |doi=10.1021/jm020153s}}</ref> Lysergic acid is made by alkaline [[hydrolysis]] of lysergamides like [[ergotamine]], a substance usually derived from the [[ergot]] [[fungus]] on [[agar plate]]. Lysergic acid can also be produced synthetically, although these processes are not used in clandestine manufacture due to their low yields and high complexity.<ref>{{cite journal |vauthors=Kornfeld EC, Fornefeld EJ, Kline GB, Mann MJ, Morrison DE, Jones RG, Woodward RB |title=The Total Synthesis of Lysergic Acid |journal=Journal of the American Chemical Society |volume=78 |issue=13 |pages=3087–3114 |year=1956 |doi=10.1021/ja01594a039|bibcode=1956JAChS..78.3087K }}</ref><ref>{{cite journal |vauthors=Inuki S, Oishi S, Fujii N, Ohno H |title=Total synthesis of (+/-)-lysergic acid, lysergol, and isolysergol by palladium-catalyzed domino cyclization of amino allenes bearing a bromoindolyl group |journal=Organic Letters |volume=10 |issue=22 |pages=5239–42 |date=November 2008 |pmid=18956869 |doi=10.1021/ol8022648 |url=https://figshare.com/articles/journal_contribution/2663242}}</ref>

Albert Hofmann synthesized LSD in the following manner: (1) hydrazinolysis of ergotamine into D- and L-isolysergic acid hydrazide, (2) separation of the enantiomers with di-(''p''-toluyl)-D-tartaric acid to get D-isolysergic acid hydrazide, (3) enantiomerization into D-lysergic acid hydrazide, (4) substitution with [[Nitrous acid|HNO<sub>2</sub>]] to D-lysergic acid azide and (5) finally substitution with [[diethylamine]] to form D-lysergic acid diethylamide.<ref name="Nichols2018a" />

The precursor for LSD, [[lysergic acid]], has been produced by [[GMO]] [[baker's yeast]].<ref>{{cite web |author=((National University of Singapore, Yong Loo Lin School of Medicine)) |date=10 February 2022 |title=Harvesting baker's yeast for aging-related therapeutics |website=ScienceDaily |url=https://www.sciencedaily.com/releases/2022/02/220210154135.htm |access-date=2023-05-04 |archive-date=November 27, 2022 |archive-url=https://web.archive.org/web/20221127230250/https://www.sciencedaily.com/releases/2022/02/220210154135.htm |url-status=live }} '''Journal Reference:''' {{cite journal |vauthors=Wong G, Lim LR, Tan YQ, Go MK, Bell DJ, Freemont PS, Yew WS |title=Reconstituting the complete biosynthesis of D-lysergic acid in yeast |journal=Nature Communications |volume=13 |issue=1 |article-number=712 |date=February 2022 |doi=10.1038/s41467-022-28386-6 |pmid=35132076 |pmc=8821704 |bibcode=2022NatCo..13..712W}}</ref>

===Stability===
"LSD," writes the chemist [[Alexander Shulgin]], "is an unusually fragile molecule ... As a salt, in water, cold, and free from air and light exposure, it is stable indefinitely."<ref name="TiHKAL" />

LSD has two [[labile]] protons at the tertiary stereogenic C5 and C8 positions, rendering these centers prone to [[epimerisation]]. The C8 proton is more labile due to the electron-withdrawing [[carboxamide]] attachment, but the removal of the [[chiral]] proton at the C5 position (which was once also an alpha proton of the parent molecule [[tryptophan]]) is assisted by the inductively withdrawing nitrogen and pi electron delocalisation with the [[indole]] ring.{{Citation needed|date=May 2011}}

LSD also has [[enamine]]-type reactivity because of the electron-donating effects of the indole ring. Because of this, [[chlorine]] destroys LSD molecules on contact; even though chlorinated tap water contains only a slight amount of chlorine, the small quantity of compound typical to an LSD solution will likely be eliminated when dissolved in tap water.<ref name="TiHKAL" /> The [[covalent bond|double bond]] between the 8-position and the [[aromatic hydrocarbon|aromatic ring]], being conjugated with the indole ring, is susceptible to [[nucleophilic]] attacks by water or [[alcohol (chemistry)|alcohol]], especially in the presence of UV or other kinds of light. LSD often converts to [[lumi-LSD]] (10-hydroxy-9,10-dihydro-LSD), which is inactive in human beings.<ref name="TiHKAL" />

A controlled study was undertaken to determine the stability of LSD in pooled urine samples.<ref>{{cite journal | vauthors = Li Z, McNally AJ, Wang H, Salamone SJ | title = Stability study of LSD under various storage conditions | journal = Journal of Analytical Toxicology | volume = 22 | issue = 6 | pages = 520–5 | date = October 1998 | pmid = 9788528 | doi = 10.1093/jat/22.6.520 | doi-access = free }}</ref>

The concentrations of LSD in urine samples were followed over time at various temperatures, in different types of storage containers, at various exposures to different wavelengths of light, and at varying pH values. These studies demonstrated no significant loss in LSD concentration at 25{{nbsp}}°C for up to four weeks. After four weeks of incubation, a 30% loss in LSD concentration at 37{{nbsp}}°C and up to a 40% at 45{{nbsp}}°C were observed. Urine fortified with LSD and stored in amber glass or nontransparent polyethylene containers showed no change in concentration under any light conditions. The stability of LSD in transparent containers under light depended on the distance between the light source and the samples, the wavelength of light, exposure time, and the light intensity. After prolonged exposure to heat in alkaline pH conditions, 10 to 15% of the parent LSD epimerized to iso-LSD. Under acidic conditions, less than 5% of the LSD was converted to iso-LSD. It was also demonstrated that trace amounts of metal ions in the buffer or urine could catalyze the decomposition of LSD and that this process could be avoided by the addition of [[EDTA]].

===Detection===
[[File:LSD Ehrlich reagent test.jpg|thumb|[[Ehrlich's reagent]] can be used to test for the presence of LSD in a sample, turning purple upon reaction.<ref name="LSDEMCDDA">{{cite web |url=https://www.emcdda.europa.eu/publications/drug-profiles/lsd_en |title=Lysergide (LSD) drug profile |website=[[European Monitoring Centre for Drugs and Drug Addiction]] (EMCDDA) |access-date=15 May 2023 |url-status=live |archive-url=https://web.archive.org/web/20230202152854/https://www.emcdda.europa.eu/publications/drug-profiles/lsd_en |archive-date=2 February 2023}}</ref>]]

LSD can be detected in concentrations larger than approximately 10% in a sample using [[Ehrlich's reagent]] and Hofmann's reagent. However, detecting LSD in human tissues is more challenging due to its active dose being significantly lower (in [[micrograms]]) compared to most other drugs (in [[milligrams]]).<ref name="ReferenceA">{{Cite journal | vauthors = Appel JB, Whitehead WE, Freedman DX |date= July 1968 |title=Motivation and the behavioral effects of LSD |journal=Psychonomic Science |language=en |volume=12 |issue=7 |pages=305–306 |doi=10.3758/BF03331322 |s2cid=144527673 |issn=0033-3131|doi-access=free }}</ref>

LSD may be quantified in urine for drug testing programs, in plasma or serum to confirm poisoning in hospitalized victims, or in whole blood for forensic investigations. The parent drug and its major metabolite are unstable in biofluids when exposed to light, heat, or alkaline conditions, necessitating protection from light, low-temperature storage, and quick analysis to minimize losses.<ref>R. Baselt, ''Disposition of Toxic Drugs and Chemicals in Man'', 12th edition, Biomedical Publications, Foster City, CA, 2020, pp. 1197–1199.</ref> Maximum plasma concentrations are typically observed 1.4 to 1.5 hours after oral administration of 100{{nbsp}}μg and 200{{nbsp}}μg, respectively, with a plasma half-life of approximately 2.6 hours (ranging from 2.2 to 3.4 hours among test subjects).<ref>{{cite journal | vauthors = Dolder PC, Schmid Y, Steuer AE, Kraemer T, Rentsch KM, Hammann F, Liechti ME | title = Pharmacokinetics and Pharmacodynamics of Lysergic Acid Diethylamide in Healthy Subjects | journal = Clinical Pharmacokinetics | volume = 56 | issue = 10 | pages = 1219–1230 | date = October 2017 | pmid = 28197931 | doi = 10.1007/s40262-017-0513-9 | pmc = 5591798 }}</ref>

Due to its potency in microgram quantities, LSD is often not included in standard pre-employment urine or hair analyses.<ref name="ReferenceA"/><ref name="pmid36753839">{{cite journal |vauthors=Jiaming Z, Xin W, Jiali Z, Hang R, Yunli Z, Ping X |title=Concentrations of LSD, 2-oxo-3-hydroxy-LSD, and iso-LSD in hair segments of 18 drug abusers |journal=Forensic Science International |volume=344 |date=March 2023 |article-number=111578 |pmid=36753839 |doi=10.1016/j.forsciint.2023.111578| s2cid=256574276}}</ref> However, advanced [[liquid chromatography–mass spectrometry]] methods can detect LSD in biological samples even after a single use.<ref name="pmid36753839"/>

===Analogues===
{{Main|Lysergamides|Partial lysergamide}}
{{See also|Lizard Labs}}
[[File:Structural modifications of the psychedelic drug LSD.png|thumb|right|400px|class=skin-invert-image|Major types of [[structural modification]]s of LSD.]]

A variety of LSD [[structural analogue|analogue]]s are known.<ref name="Shulgin2003">{{cite book | vauthors = Shulgin AT | chapter=Basic Pharmacology and Effects | pages=67–137 | veditors = Laing RR | title=Hallucinogens: A Forensic Drug Handbook | publisher=Elsevier Science | series=Forensic Drug Handbook Series | year=2003 | isbn=978-0-12-433951-4 | url=https://books.google.com/books?id=l1DrqgobbcwC | chapter-url=https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=6bb3a7499da8e9852b39cd4db16891147c83f5c6 | access-date=1 February 2025}}</ref><ref name="JacobShulgin1994">{{cite journal | vauthors = Jacob P, Shulgin AT | title = Structure-activity relationships of the classic hallucinogens and their analogs | journal = NIDA Res Monogr | volume = 146 | issue = | pages = 74–91 | date = 1994 | pmid = 8742795 | doi = | url = https://archives.nida.nih.gov/sites/default/files/monograph146.pdf#page=79 | archive-url = https://web.archive.org/web/20230805004551/https://archives.nida.nih.gov/sites/default/files/monograph146.pdf#page=79 | archive-date = August 5, 2023 }}</ref><ref name="Shulgin1982">{{cite book |vauthors=Shulgin AT | chapter=Chemistry of Psychotomimetics | pages = 3–29 | veditors = Hoffmeister F, Stille G | title=Psychotropic Agents, Part III: Alcohol and Psychotomimetics, Psychotropic Effects of Central Acting Drugs | series=Handbook of Experimental Pharmacology | publisher=Springer Berlin Heidelberg |location=Berlin |date=1982 | volume=55 / 3 |isbn=978-3-642-67772-4 | oclc = 8130916 | doi=10.1007/978-3-642-67770-0_1 | url = https://books.google.com/books?id=mrT8CAAAQBAJ | chapter-url = https://bitnest.netfirms.com/external/10.1007/978-3-642-67770-0_1}}</ref><ref name="Shulgin1980">{{cite book | author = Alexander T. Shulgin | chapter = Hallucinogens | pages = 1109–1137 | chapter-url = https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=6ac0c892ee380436f614d3aae0686ef617b2e0c5 | veditors = Burger A, Wolf ME | title = Burger's Medicinal Chemistry | edition = 4 | volume = 3 | date = 1980 | publisher = Wiley | location = New York | isbn = 978-0-471-01572-7 | oclc = 219960627 | url = https://books.google.com/books?id=2b3wAAAAMAAJ}}</ref><ref name="TiHKAL" /> Many of them retain psychedelic effects similarly to LSD, although most have reduced [[potency (pharmacology)|potency]] and none are notably more potent than LSD.<ref name="Shulgin2003" /><ref name="JacobShulgin1994" /><ref name="Shulgin1982" /><ref name="Shulgin1980" /><ref name="Mangner1978">{{cite thesis | vauthors = Mangner TJ | degree = Ph.D. | publisher = University of Michigan | title=Potential Psychotomimetic Antagonists. N,n -diethyl-1-methyl-3-aryl-1, 2, 5, 6-tetrahydropyridine-5-carboxamides. | date=1978 | doi=10.7302/11268 | url=https://www.proquest.com/openview/f845a6810749d00f70305960adfde737/ | archive-url=https://web.archive.org/web/20250330031605/https://media.proquest.com/media/hms/ORIG/2/9yQxJ?cit%3Aauth=MANGNER%2C+THOMAS+JOSEPH&cit%3Atitle=POTENTIAL+PSYCHOTOMIMETIC+ANTAGONISTS.+N%2CN+...&cit%3Apub=ProQuest+Dissertations+and+Theses&cit%3Avol=&cit%3Aiss=&cit%3Apg=&cit%3Adate=1978&ic=true&cit%3Aprod=ProQuest+Dissertations+%26+Theses+Global&_a=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&_s=QP3F3liRMGFAbHtX3wDWE8eO1gs%3D#page=22 | archive-date=30 March 2025}}</ref> Examples include [[ergine]] (lysergic acid amide; LSA), [[isoergine]] (iso-LSA), [[lysergic acid hydroxyethylamide]] (LSH), [[ergonovine]] (ergometrine), [[methylergonovine]] (methylergometrine), [[methysergide]], [[ETH-LAD]], [[PRO-LAD]], [[AL-LAD]], [[1-methyl-LSD]] (MLD-41), [[MiPLA]], and [[LA-SS-Az]] (LSZ), among many others.<ref name="Shulgin2003" /><ref name="RutschmannStadler1978">{{cite book | vauthors = Rutschmann J, Stadler PA | chapter=Chemical Background | veditors=Berde B, Schild HO | title=Ergot Alkaloids and Related Compounds | publisher=Springer Berlin Heidelberg | publication-place=Berlin, Heidelberg | date=1978 | isbn=978-3-642-66777-0 | doi=10.1007/978-3-642-66775-6_2 | pages=29–85 | series=Handbook of Experimental Pharmacology (HEP) | volume=49}}</ref><ref name="Fanchamps1978">{{cite book | vauthors = Fanchamps A | chapter=Some Compounds With Hallucinogenic Activity | veditors=Berde B, Schild HO | title=Ergot Alkaloids and Related Compounds | publisher=Springer Berlin Heidelberg | publication-place=Berlin, Heidelberg | date=1978 | isbn=978-3-642-66777-0 | doi=10.1007/978-3-642-66775-6_8 | pages=567–614 | series=Handbook of Experimental Pharmacology (HEP) | volume=49 | chapter-url=https://bibliography.maps.org/resources/download/8769| archive-url=https://web.archive.org/web/20250330033128/https://bibliography.maps.org/resources/download/8769 | archive-date=March 30, 2025 }}</ref> Presumed or known [[prodrug]]s of LSD, including [[1A-LSD]] (ALD-52), [[1P-LSD]], and [[1V-LSD]], have been developed or encountered.<ref name="SchifanoVentoScherbaum2023">{{cite journal | vauthors = Schifano F, Vento A, Scherbaum N, Guirguis A | title = Stimulant and hallucinogenic novel psychoactive substances; an update | journal = Expert Rev Clin Pharmacol | volume = 16 | issue = 11 | pages = 1109–1123 | date = 2023 | pmid = 37968919 | doi = 10.1080/17512433.2023.2279192 | url = | hdl = 2299/27223 | hdl-access = free }}</ref><ref name="Ponce2024">{{cite journal | vauthors = Ponce JC | title=The use of prodrugs as drugs of abuse | journal=WIREs Forensic Science | volume=6 | issue=3 | date=2024 | issn=2573-9468 | doi=10.1002/wfs2.1514 | doi-access=free | article-number=e1514 }}</ref> Some non-[[hallucinogen]]ic LSD analogues, such as [[lisuride]] and [[2-bromo-LSD]] (BOL-148), are known as well.<ref name="GumpperNichols2024">{{cite journal | vauthors = Gumpper RH, Nichols DE | title = Chemistry/structural biology of psychedelic drugs and their receptor(s) | journal = Br J Pharmacol | volume = | issue = | date = October 2024 | article-number = bph.17361 | pmid = 39354889 | doi = 10.1111/bph.17361 | url = }}</ref><ref name="PfaffHuangMarona-Lewicka1994" /><ref name="Nichols2012">{{cite journal | vauthors = Nichols DE | title=Structure–activity relationships of serotonin 5-HT 2A agonists | journal=Wiley Interdisciplinary Reviews: Membrane Transport and Signaling | volume=1 | issue=5 | date=2012 | issn=2190-460X | doi=10.1002/wmts.42 | doi-access=free | pages=559–579 | access-date=22 March 2025 | url=https://citeseerx.ist.psu.edu/document?repid=rep1&type=pdf&doi=e28e0e22c3145af5a787c34fbedbaa8f81e1ed6b}}</ref> They are lower-[[intrinsic activity|efficacy]] [[serotonin]] [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]] [[partial agonist]]s and can notably act as [[hallucinogen antagonist]]s against LSD.<ref name="PfaffHuangMarona-Lewicka1994">{{cite journal | vauthors = Pfaff RC, Huang X, Marona-Lewicka D, Oberlender R, Nichols DE | title = Lysergamides revisited | journal = NIDA Res Monogr | volume = 146 | issue = | pages = 52–73 | date = 1994 | pmid = 8742794 | doi = | url = https://archives.nida.nih.gov/sites/default/files/monograph146.pdf#page=57| archive-url = https://web.archive.org/web/20230805004551/https://archives.nida.nih.gov/sites/default/files/monograph146.pdf#page=57| archive-date = August 5, 2023}}</ref><ref name="Nichols2012" /> In addition to [[lysergamide]] [[chemical derivative|derivative]]s, [[simplified LSD analogue|simplified or "partial" LSD analogues]] or [[seco-LSD]] compounds, such as [[NDTDI]] (8,10-seco-LSD), [[DEIMDHPCA]] (3,5-seco-LSD), [[10,11-seco-LSD]], and [[N-DEAOP-NMT|''N''-DEAOP-NMT]], are known.<ref name="Shulgin1976">{{cite book | veditors=Gordon M | title=Psychopharmacological Agents: Use, Misuse and Abuse | series=Medicinal Chemistry: A Series of Monographs | volume=4 | vauthors = Shulgin AT | chapter=Psychotomimetic Agents | date=1976 | isbn=978-0-12-290559-9 | doi=10.1016/b978-0-12-290559-9.50011-9 | pages=59–146 | publisher=Academic Press | url=https://bitnest.netfirms.com/external/10.1016/B978-0-12-290559-9.50011-9 | quote = The largest number of structural analogs of LSD that have been prepared involve the opening of one or more of the rings of the parent lysergic acid system. [...] A recent review covers this chemistry (Campaigne and Knapp, 1971), but there is apparently no human psychopharmacology as yet known.}}</ref><ref name="Nichols1973">{{cite thesis | vauthors = [[David E. Nichols|Nichols DE]] | title = Potential Psychotomimetics: Bromomethoxyamphetamines and Structural Congeners of Lysergic Acid | date = May 1973 | publisher = [[University of Iowa]] | page = 23 | oclc = 1194694085 | url = https://bitnest.netfirms.com/external/Theses/Nichols1973#page=32}}</ref><ref name="CampaigneKnapp1971">{{cite journal | vauthors = Campaigne E, Knapp DR | title = Structural analogs of lysergic acid | journal = J Pharm Sci | volume = 60 | issue = 6 | pages = 809–814 | date = June 1971 | pmid = 4942861 | doi = 10.1002/jps.2600600602 | bibcode = 1971JPhmS..60..809C | url = }}</ref><ref name="WO2021076572">{{cite patent | country = WO | number = 2021076572 | inventor = [[David E. Olson|Olsen DE]], Dunlap L, Wagner F, Chytil M, Powell NA | status = | title = Ergoline-like compounds for promoting neural plasticity | pubdate = 22 April 2021 | gdate = | fdate = 14 October 2020 | pridate = 14 October 2020 | assign1 = [[Delix Therapeutics, Inc.]] | assign2 = [[The Regents of the University of California]] | url =https://patents.google.com/patent/WO2021076572/ }}</ref> A notable [[bioisostere]] of LSD is [[JRT (drug)|JRT]], the [[isotryptamine]] analogue of LSD and a psychedelic and [[psychoplastogen]] which is under investigation for the potential treatment of [[schizophrenia]].<ref name="TuckDunlapKhatib2025">{{cite journal | vauthors = Tuck JR, Dunlap LE, Khatib YA, Hatzipantelis CJ, Weiser Novak S, Rahn RM, Davis AR, Mosswood A, Vernier AM, Fenton EM, Aarrestad IK, Tombari RJ, Carter SJ, Deane Z, Wang Y, Sheridan A, Gonzalez MA, Avanes AA, Powell NA, Chytil M, Engel S, Fettinger JC, Jenkins AR, Carlezon WA, Nord AS, Kangas BD, Rasmussen K, Liston C, Manor U, Olson DE | title = Molecular design of a therapeutic LSD analogue with reduced hallucinogenic potential | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 122 | issue = 16 | article-number = e2416106122 | date = April 2025 | pmid = 40228113 | doi = 10.1073/pnas.2416106122 | doi-access = free | pmc = 12037037 | bibcode = 2025PNAS..12216106T }}</ref><ref name="Dunlap2022">{{cite thesis | vauthors =  Dunlap L | degree = Ph.D. | publisher = University of California, Davis | chapter=Chapter 5. An Analog of LSD With Antipsychotic Potential | pages=105–114 | title=Development of Non-Hallucinogenic Psychoplastogens | date = 2022 | url=https://escholarship.org/content/qt5qr3w0gm/qt5qr3w0gm.pdf#page=112}}</ref>

==History==
{{Quote box| quote= ... affected by a remarkable restlessness, combined with a slight dizziness. At home I lay down and sank into a not unpleasant intoxicated-like condition, characterized by an extremely stimulated imagination. In a dreamlike state, with eyes closed (I found the daylight to be unpleasantly glaring), I perceived an uninterrupted stream of fantastic pictures, extraordinary shapes with intense, [[kaleidoscope|kaleidoscopic]] play of colors. After some two hours this condition faded away.|source= —Albert Hofmann, on his first experience with LSD<ref name="hofmann1980">{{cite book | vauthors = Hofmann A |url=http://www.psychedelic-library.org/child.htm |title=LSD—My Problem Child |access-date=April 19, 2010 |via=The Psychedelic Library |archive-url=https://web.archive.org/web/20171215043651/http://www.psychedelic-library.org/child.htm |archive-date=15 December 2017 |url-status=live |publisher=McGraw-Hill |date=1980 |isbn=0-07-029325-2}}</ref>{{rp|p=15}}|width=25em}}{{Main|History of LSD}}

LSD was first synthesized on November 16, 1938<ref>{{cite journal |vauthors=Hofmann A |author-link=Albert Hofmann| translator=Ott J |title=LSD Ganz Persönlich |trans-title=LSD: Completely Personal |date=Summer 1969 |url=http://www.maps.org/news-letters/v06n3/06346hof.html |journal=MAPS |volume=6 |issue=69 |language=de |archive-url=https://web.archive.org/web/20131206032629/http://www.maps.org/news-letters/v06n3/06346hof.html |archive-date=6 December 2013}}</ref> by Swiss chemist [[Albert Hofmann]] at the [[Sandoz]] Laboratories in [[Basel]], Switzerland as part of a large research program searching for medically useful [[ergot alkaloid]] derivatives.<ref>{{cite book |url=https://books.google.com/books?id=TNXeDAAAQBAJ&pg=PT342 |title=Medicinal Chemistry: A Molecular and Biochemical Approach |vauthors=Nogrady T, Weaver DF |date=2005 |publisher=Oxford University Press |isbn=978-0-19-028296-7 |page=342 |language=en |access-date=March 14, 2020 |url-status=live |archive-url=https://web.archive.org/web/20210308133740/https://www.google.com/books/edition/Medicinal_Chemistry/TNXeDAAAQBAJ?hl=en&gbpv=1&dq=%22LysergS%C3%A4ureDiethylamid%22+abreviation+LSD&pg=PT342 |archive-date=March 8, 2021}}</ref>

LSD was synthesised from [[lysergic acid]], a chemical derived from the [[hydrolysis]] of the [[alkaloid]] [[ergotamine]], which can be found in the grain-infecting fungus [[ergot]].<ref name="EU2018" /><ref name="NIH2018C" /> It was the 25th substance of various [[lysergamides]] that Hofmann synthesized from lysergic acid while trying to develop a new [[analeptic]], hence its alternate name, LSD-25.

[[Image:Albert Hofmann.jpg|thumb|[[Albert Hofmann]] in 2006.]]

LSD's [[psychedelic]] properties were discovered 5 years later when Hofmann himself accidentally ingested an unknown quantity of the chemical.<ref name="hyponichols">{{cite web |title=Hypothesis on Albert Hofmann's Famous 1943 "Bicycle Day" |url=http://www.erowid.org/general/conferences/conference_mindstates4_nichols.shtml |access-date=September 27, 2007 |vauthors=Nichols D |date=May 24, 2003 |website=Hofmann Foundation |archive-date=September 22, 2007 |archive-url=https://web.archive.org/web/20070922215008/http://www.erowid.org/general/conferences/conference_mindstates4_nichols.shtml |url-status=live}}</ref> The first intentional ingestion of LSD occurred on April 19, 1943,<ref name="hofmann1980" /> when Hofmann ingested 250 [[μg]] of LSD. He said this would be a threshold dose based on the doses of other ergot alkaloids; however, Hofmann found the effects to be much stronger than he anticipated.<ref name="histlsd">{{cite web |url=http://www.a1b2c3.com/drugs/lsd01.htm|title=History Of LSD |access-date=September 27, 2007 |vauthors=Hofmann A |archive-url=https://web.archive.org/web/20070904212518/http://www.a1b2c3.com/drugs/lsd01.htm |archive-date=September 4, 2007}}</ref> Information about synthesizing LSD was first published in [[scientific literature]] by Hofmann and his colleague, [[psychiatrist]] [[Werner Stoll]] in 1943; a description of LSD's hallucinogenic effects was later published by Stoll in 1947.<ref name="Gach2008">{{cite book | vauthors = Gach J | title=History of Psychiatry and Medical Psychology | chapter=Biological Psychiatry in the Nineteenth and Twentieth Centuries | publisher=Springer US | publication-place=Boston, MA | date=2008 | isbn=978-0-387-34707-3 | doi=10.1007/978-0-387-34708-0_12 | pages=381–418 | url=https://www.timothydavidson.com/Library/Books/Wallace-2008-History%20of%20Psychiatry%20and%20Medical%20Psychology/Wallace%20and%20Gach-2008-History%20of%20Psychiatry%20and%20Medical%20Psychology.pdf#page=413 | archive-url=https://web.archive.org/web/20250319140308/https://www.timothydavidson.com/Library/Books/Wallace-2008-History%20of%20Psychiatry%20and%20Medical%20Psychology/Wallace%20and%20Gach-2008-History%20of%20Psychiatry%20and%20Medical%20Psychology.pdf#page=413 | archive-date=March 19, 2025 | quote=In 1938 the Swiss chemist Albert Hofmann produced lysergic acid diethylamide (LSD)—the first, and most prominent, of these chemically synthesized agents—in the course of a systematic investigation of partially synthetic amides of lysergic acid in the Sandoz Pharmaceutical Laboratories in Basel (Hofmann 1970). [Taking] LSD by accident in 1943, Hofmann discovered its psychoactivity. He then experimented with it on himself and found that it produced a peculiar restlessness, extreme activity of the imagination, and an uninterrupted stream of images. Hofmann did not publish the results of his experiment, though he became quite famous later. Hofmann and Arthur Stoll, the head of the Sandoz pharmaceutical laboratory in Basle, published the first paper on the synthesis of LSD in 1943, while Stoll went on to publish the first paper on the effects of lysergic diethylamide acid in 1947. [...] Stoll, Arthur and Hofmann, Albert. 1943. Partialsynthese von Alkaloiden vom Typus des Ergobasins. Helv. Chim. Acta 26:944. Stoll, Arthur. 1947. Lysergsäure-diäthylamid, ein Phantastikum aus der Mutterkorngruppe. Schweiz. Arch. Neurol. Psychiat. 60:279. [The first paper on the hallucinogenic effect of LSD.]}}</ref><ref name="Horowitz1976">{{cite magazine | author=Michael Horowitz | title=Interview: Albert Hofmann | magazine=[[High Times]] | number=11 | date=July 1976 | pages=24–28, 31, 81 | url=https://bibliography.maps.org/resources/download/13725 | archive-url=https://web.archive.org/web/20250505231257/https://bibliography.maps.org/resources/download/13725 | archive-date=2025-05-05 | quote = High Times: Why was it four years from your discovery of the psychic effects of LSD [in 1943] until your report was published? [...] Hofmann: [...] After confirmation of the action of this extraordinary compound by volunteers of the Sandoz staff, Professor Arthur Stoll, who was then head of the Sandoz pharmaceutical department, asked me if I would permit his son, Werner A. Stoll—who was starting his career at the psychiatric hospital of the University of Zurich—to submit this new agent to a fundamental psychiatric study on normal volunteers and on psychiatric patients. This investigation took a rather long time, [...] This excellent and comprehensive study was not published until 1947.}}</ref><ref name="StollHofmann1943">{{cite journal | vauthors = Stoll A, Hofmann A | title=Partialsynthese von Alkaloiden vom Typus des Ergobasins. (6. Mitteilung über Mutterkornalkaloide) | trans-title=Partial synthesis of ergobasine-type alkaloids. (6th report on ergot alkaloids) | journal=Helvetica Chimica Acta | volume=26 | issue=3 | date=3 May 1943 | issn=0018-019X | doi=10.1002/hlca.19430260326 | pages=944–965| bibcode=1943HChAc..26..944S }}</ref><ref name="Stoll1947">{{cite journal | vauthors = Stoll WA | title = 11. Lysergsäure-diäthylamid, ein Phantastikum aus der Mutterkorngruppe | trans-title = 11. Lysergic Acid Diethylamide, a Hallucinogen From the Ergot Group | journal = Schweizer Archiv für Neurologie und Psychiatrie | volume = 60 | issue = | date = 1947 | pages = 279–323 | issn = 0258-7661 | url = https://bibliography.maps.org/resources/download/16963| archive-url = https://web.archive.org/web/20250401005831/https://bibliography.maps.org/resources/download/16963 | archive-date = April 1, 2025 }}</ref><ref name="Stoll1949">{{cite journal | vauthors = Stoll W | title = Ein neues, in sehr kleinen Mengen wirksames Phantastikum | trans-title = A New Phantasticum, Effective in Very Tiny Amounts | journal = Schweizer Archiv für Neurologie und Psychiatrie | volume = 64 | issue = | date = 1949 | pages = 483–484 | issn = 0258-7661 | url = https://bibliography.maps.org/resources/download/16676| archive-url = https://web.archive.org/web/20250401012040/https://bibliography.maps.org/resources/download/16676 | archive-date = April 1, 2025 }}</ref> 

===Historical pharmaceutical production and distribution===
[[Sandoz|Sandoz Laboratories]] introduced LSD as a psychiatric drug in 1947, marketing it as a psychiatric [[Panacea (medicine)|panacea]] which could serve "as a cure for everything from schizophrenia to criminal behavior, 'sexual perversions', and alcoholism."<ref name="LSD: The Drug">{{cite report |date=Oct 1995 |chapter=LSD: The Drug |title=LSD in the United States |publisher=U.S. Department of Justice, Drug Enforcement Administration |chapter-url=http://www.usdoj.gov/dea/pubs/lsd/lsd-4.htm |access-date=November 27, 2010 |archive-date=April 27, 1999 |archive-url=https://web.archive.org/web/19990427145322/http://www.usdoj.gov/dea/pubs/lsd/lsd-4.htm}}</ref> Sandoz also sent the drug for free to researchers investigating its effects.<ref name="Hofmann2009">{{Cite book |vauthors=Hofmann A |title=LSD, my problem child: reflections on sacred drugs, mysticism, and science |location=Santa Cruz, CA |publisher=Multidisciplinary Association for Psychedelic Studies |year=2009 |isbn=978-0-9798622-2-9 |edition=4th |oclc=610059315}}</ref> In 1963, the Sandoz patents on LSD expired<ref name="henderson-glass" /> and the Czech company Spofa began to produce the substance.<ref name="Hofmann2009" /> Sandoz stopped the production and distribution in 1965.<ref name="Hofmann2009" />

===Historical use in psychiatry and psychotherapy===
LSD was subject to exceptional interest within the field of psychiatry in the 1950s and early 1960s, and Sandoz distributed LSD to researchers under the trademark name Delysid in an attempt to find a marketable use for it.<ref name="Lee1992">{{Cite book |vauthors=Lee MA, Shlain B |title=Acid dreams: the complete social history of LSD: the CIA, the Sixties, and beyond |date=1992 |publisher=Grove Weidenfeld |isbn=0-8021-3062-3 |location=New York |oclc=25281992}}</ref> During this period, LSD was controversially administered to hospitalised schizophrenic autistic children, with varying degrees of therapeutic success.<ref>{{cite journal | vauthors = Freedman AM, Ebin EV, Wilson EA | title = Autistic schizophrenic children. An experiment in the use of d-lysergic acid diethylamide (LSD-25) | journal = Archives of General Psychiatry | volume = 6 | issue = 3 | pages = 203–213 | date = March 1962 | pmid = 13894863 | doi = 10.1001/archpsyc.1962.01710210019003 }}</ref><ref>{{cite journal | vauthors = Simmons JQ, Leiken SJ, Lovaas OI, Schaeffer B, Perloff B | title = Modification of autistic behavior with LSD-25 | journal = The American Journal of Psychiatry | volume = 122 | issue = 11 | pages = 1201–1211 | date = May 1966 | pmid = 5325567 | doi = 10.1176/ajp.122.11.1201 }}</ref><ref>{{cite journal | vauthors = Sigafoos J, Green VA, Edrisinha C, Lancioni GE | title = Flashback to the 1960s: LSD in the treatment of autism | journal = Developmental Neurorehabilitation | volume = 10 | issue = 1 | pages = 75–81 | date = 2007 | pmid = 17608329 | doi = 10.1080/13638490601106277 | url = https://figshare.com/articles/journal_contribution/22860110 }}</ref><ref>{{cite journal | vauthors = Abramson HA | title = The use of LSD (d-lysergic acid diethylamide) in the therapy of children (a brief review) | journal = The Journal of Asthma Research | volume = 5 | issue = 2 | pages = 139–143 | date = December 1967 | pmid = 4865578 | doi = 10.3109/02770906709104325 }}</ref> It was said to have been tried in every type of mental disorder by 1960.<ref name="BrimblecombePinder1975" /> LSD was also used in an attempt to cure [[homosexuality]].<ref name="BrimblecombePinder1975" /> Most of the early studies of LSD for psychiatric conditions were of very low quality, often lacking even [[control group]]s.<ref name="BrimblecombePinder1975" /> In 1975, it was concluded that LSD showed little difference from [[placebo]] for most conditions.<ref name="BrimblecombePinder1975" />

LSD-assisted [[psychotherapy]] was used in the 1950s and early 1960s by psychiatrists such as [[Humphry Osmond]], who pioneered the application of LSD to the treatment of [[alcoholism]], with promising results.<ref name="Lee1992" /><ref>{{Cite web |title=Psychiatric Research with Hallucinogens |website=www.druglibrary.org |url=https://www.druglibrary.org/schaffer/lsd/grob.htm |access-date=2021-07-26|archive-date=July 26, 2021|archive-url=https://web.archive.org/web/20210726203733/https://www.druglibrary.org/schaffer/lsd/grob.htm |url-status=live}}</ref><ref name="Use of d-lysergic acid diethylamide" /><ref name="Lysergic acid diethylamide LSD fo">{{cite journal |vauthors=Krebs TS, Johansen PØ |title=Lysergic acid diethylamide (LSD) for alcoholism: meta-analysis of randomized controlled trials |journal=Journal of Psychopharmacology |volume=26 |issue=7 |pages=994–1002 |date=July 2012 |pmid=22406913 |doi=10.1177/0269881112439253 |s2cid=10677273}}</ref> Osmond coined the term "psychedelic," meaning "mind manifesting," as a term for LSD and related [[hallucinogen]]s, superseding the previously held "[[psychotomimetic]]" model (in which LSD was believed to mimic [[schizophrenia]]). In contrast to schizophrenia, LSD can induce [[Transcendence (philosophy)#Contemporary philosophy|transcendent]] experiences, with lasting psychological benefit.<ref name="Nichols2016" /><ref name="Lee1992" /> 

===Historical use by government agencies=== 
[[File:Effects_of_Lysergic_Acid_Diethylamide_(LSD)_on_Troops_Marching.webm|thumb|upright=1.35|'Effects of Lysergic Acid Diethylamide (LSD) on Troops Marching' – 16mm film produced by the United States military circa 1958]] Beginning in the 1950s, the US [[Central Intelligence Agency]] (CIA) began a research program code-named [[Project MKUltra]].<ref>{{Cite book | vauthors = Marks J |title=The Search for the Manchurian Candidate: The CIA and Mind Control |date=1978 |publisher=Times Books |isbn=07139-12790 |location=U.S.A. |page=57}}</ref> The CIA introduced LSD to the United States, purchasing the entire world's supply for $240,000 and propagating the LSD through CIA [[front organizations]] to American hospitals, clinics, prisons, and research centers.<ref>{{cite news |title=The CIA's Secret Quest For Mind Control: Torture, LSD And A 'Poisoner In Chief' |url=https://www.npr.org/2019/09/09/758989641/the-cias-secret-quest-for-mind-control-torture-lsd-and-a-poisoner-in-chief |website=NPR.org |access-date=6 October 2019 |language=en |archive-date=June 28, 2021 |archive-url=https://web.archive.org/web/20210628081520/https://www.npr.org/2019/09/09/758989641/the-cias-secret-quest-for-mind-control-torture-lsd-and-a-poisoner-in-chief |url-status=live }}</ref> Experiments included administering LSD to CIA employees, military personnel, doctors, other government agents, prostitutes, mentally ill patients, and members of the general public to study their reactions (usually without the subjects' knowledge), the most well-known example of this being [[Operation Midnight Climax]].<ref name="Lee1992" /> The project was revealed in the US congressional [[United States President's Commission on CIA activities within the United States|Rockefeller Commission report]] in 1975. However, the extent of the experiments conducted under Project MKUltra are still mostly unknown, as acting CIA director Richard Helms destroyed many of the key documents related to MKUltra in 1973.<ref>{{Cite book | vauthors = Marks J |title=The Search for The Manchurian Candidate: The CIA and Mind Control |publisher=Times Books |year=1978 |publication-date=1978 |page=97 |language=English}}</ref> According to declassified CIA documents, it's possible that the American agency spread LSD amongst civilians in Europe in the 1950s.<ref>{{Cite web |date=2010-03-11 |title=French bread spiked with LSD in CIA experiment |url=https://www.telegraph.co.uk/news/worldnews/europe/france/7415082/French-bread-spiked-with-LSD-in-CIA-experiment.html |access-date=2025-04-01 |website=The Telegraph |language=en}}</ref><ref>{{Cite news |date=2010-08-23 |title=Pont-Saint-Esprit poisoning: Did the CIA spread LSD? |url=https://www.bbc.com/news/world-10996838 |access-date=2025-04-01 |work=BBC News |language=en-GB}}</ref> LSD was also one of several psychoactive substances evaluated by the [[U.S. Army Chemical Corps]] as possible non-lethal incapacitants in the [[Edgewood Arsenal human experiments]].<ref name="Lee1992" />

===History of cultural impact===
The use of LSD was most widespread from the 1960s through the 1980s.<ref name="EU2018" /> In the 1960s, LSD and other psychedelics were adopted by and became synonymous with the [[Hippie]] [[counterculture movement]] due to their perceived ability to expand consciousness. This resulted in LSD being viewed as a cultural threat to American values and the [[Vietnam War]] effort, and it was designated as a [[List of Schedule I drugs (US)|Schedule I]] (illegal for medical as well as recreational use) substance in 1968.<ref name="United States Congress House Committee on Interstate and Foreign Commerce Subcommittee on Public Health and Welfare 1968" /> It was listed as a [[Convention on Psychotropic Substances#Schedule I|Schedule I controlled substance]] by the [[United Nations]] in 1971 and currently has no approved medical uses.<ref name="EU2018" /> 

Several figures, including [[Aldous Huxley]], [[Timothy Leary]], and [[Alfred Matthew Hubbard|Al Hubbard]], had begun to advocate the consumption of LSD as it became central to the counterculture of the 1960s.<ref>{{cite web |url=http://www.druglibrary.org/schaffer/Library/studies/cu/CU50.html |title=How LSD was popularized |vauthors=Brecher EM |collaboration=Editors of Consumer Reports Magazine |date=1972 |publisher=Druglibrary.org |access-date=20 June 2012 |url-status=live |archive-url=https://web.archive.org/web/20120513233708/http://druglibrary.org/schaffer/Library/studies/cu/CU50.html |archive-date= 13 May 2012}}</ref> In the early 1960s, the use of LSD and other hallucinogens was advocated by new proponents of consciousness expansion such as Leary, Huxley, [[Alan Watts]] and [[Arthur Koestler]],<ref>{{cite web |vauthors=Applebaum A |author-link=Anne Applebaum |url=http://www.huffingtonpost.com/2010/01/26/did-the-death-of-communis_n_435939.html |title=Did The Death Of Communism Take Koestler And Other Literary Figures With It? |work=[[The Huffington Post]] |date=26 January 2010 |archive-url=http://web.archive.org/web/20171107233333/https://www.huffingtonpost.com/2010/01/26/did-the-death-of-communis_n_435939.html |archive-date= 2017-11-07}}</ref><ref>{{cite web |title=''Out-Of-Sight!'' SMiLE Timeline |url=http://pages.cthome.net/tobelman/The_Out-Of-Sight_SMiLE_Site.html|access-date=October 30, 2011|archive-url=https://web.archive.org/web/20100201234435/http://pages.cthome.net/tobelman/The_Out-Of-Sight_SMiLE_Site.html |archive-date=February 1, 2010}}</ref> and, according to historians, they profoundly influenced the thinking of the new generation of youth.<ref>{{cite book |vauthors=Veysey LR |title=[[The Communal Experience: Anarchist and Mystical Communities in Twentieth-Century America]] |location=Chicago IL |publisher=University of Chicago Press |date=1978 |isbn=0-226-85458-2 |page=437}}</ref>

===Historical legality and modern-day usage in the United States===
On October 24, 1968, possession of LSD was made illegal in the United States.<ref>{{cite web |url=http://www.erowid.org/psychoactives/law/law_fed_staggers-dodd.pdf |author=United States Congress |title=Staggers-Dodd Bill, Public Law 90-639 |date=October 24, 1968 |access-date=September 8, 2009 |url-status=live |archive-url=https://web.archive.org/web/20100509025200/http://www.erowid.org/psychoactives/law/law_fed_staggers-dodd.pdf |archive-date=May 9, 2010}}</ref> The last [[FDA]] approved study of LSD in patients ended in 1980, while a study in healthy volunteers was made in the late 1980s. Legally approved and regulated psychiatric use of LSD continued in Switzerland until 1993.<ref>{{cite web |url=http://www.maps.org/news-letters/v05n3/05303psy.html |vauthors=Gasser P |title=Psycholytic Therapy with MDMA and LSD in Switzerland |year=1994 |access-date=September 8, 2009 |url-status=live | archive-date=October 11, 2009 |archive-url=https://web.archive.org/web/20091011083518/http://www.maps.org/news-letters/v05n3/05303psy.html}}</ref>

{{As of|2017}}, about 10% of people in the United States have used LSD at some point in their lives, while 0.7% have used it in the last year.<ref name="NIH2018B" /> The use of LSD among US adults increased by 56.4% from 2015 to 2018.<ref>{{cite journal |vauthors=Yockey RA, Vidourek RA, King KA |title=Trends in LSD use among US adults: 2015–2018 |journal=Drug and Alcohol Dependence |volume=212 |article-number=108071 |date=July 2020 |pmid=32450479 |doi=10.1016/j.drugalcdep.2020.108071 |s2cid=218893155}}</ref> In November 2020, Oregon became the first US state to [[decriminalization|decriminalize]] possession of small amounts of LSD after voters approved [[Oregon Ballot Measure 110|Ballot Measure 110]].<ref>{{Cite web|title=Oregon becomes first state to legalize magic mushrooms as more states ease drug laws in 'psychedelic renaissance'|vauthors=Feuer W|date=November 4, 2020 |url=https://www.cnbc.com/2020/11/04/oregon-becomes-first-state-to-legalize-magic-mushrooms-as-more-states-ease-drug-laws.html |website=CNBC|access-date=November 7, 2020 |url-status=live|archive-date=November 4, 2020|archive-url=https://web.archive.org/web/20201104155737/https://www.cnbc.com/2020/11/04/oregon-becomes-first-state-to-legalize-magic-mushrooms-as-more-states-ease-drug-laws.html}}</ref>

==Society and culture==
===Counterculture===
By the mid-1960s, the youth [[counterculture]]s in California, particularly in San Francisco, had widely adopted the use of hallucinogenic drugs, including LSD. The first major underground LSD factory was established by [[Owsley Stanley]].<ref name=DeRogatispp8-9>{{cite book |vauthors=DeRogatis J |title=Turn On Your Mind: Four Decades of Great Psychedelic Rock |location=Milwaukie, Michigan |publisher=Hal Leonard |date=2003 |isbn=0-634-05548-8 |pages=8–9}}</ref> Around this time, the [[Merry Pranksters]], associated with novelist [[Ken Kesey]], organized the [[Acid Tests]], events in San Francisco involving LSD consumption, accompanied by light shows and improvised music.<ref name=pc41>{{cite web |url=https://digital.library.unt.edu/ark:/67531/metadc19800/m1/ |title=Show 41 – The Acid Test: Psychedelics and a sub-culture emerge in San Francisco. [Part 1&#93;: UNT Digital Library | vauthors = Gilliland J |year=1969 |author-link=John Gilliland |website=[[Pop Chronicles]] |publisher=Digital.library.unt.edu |format=audio |access-date=May 6, 2011 |url-status=live |archive-url=https://web.archive.org/web/20111109144934/http://digital.library.unt.edu/ark:/67531/metadc19800/m1/ |archive-date=November 9, 2011}}</ref><ref name=Hicks2000p60>{{cite book | vauthors = Hicks M | title = Sixties Rock: Garage, Psychedelic, and Other Satisfactions Music in American Life | location = Chicago, IL | publisher = University of Illinois Press | date = 2000 | isbn = 0-252-06915-3 | page = 60 }}</ref> Their activities, including cross-country trips in a psychedelically-decorated bus and interactions with major figures of the beat movement, were later documented in [[Tom Wolfe]]'s ''[[The Electric Kool-Aid Acid Test]]'' (1968).<ref name=Mann2009p87>{{cite book | vauthors = Mann J | title = Turn on and Tune in: Psychedelics, Narcotics and Euphoriants | publisher = Royal Society of Chemistry | date = 2009 | isbn = 978-1-84755-909-8 | page = 87 }}</ref>

In San Francisco's Haight-Ashbury neighborhood, the Psychedelic Shop was opened in January 1966 by brothers Ron and Jay Thelin to promote the safe use of LSD. This shop played a significant role in popularizing LSD in the area and establishing [[Haight-Ashbury]] as the epicenter of the hippie counterculture. The Thelins also organized the [[Love Pageant Rally]] in Golden Gate Park in October 1966, protesting against California's ban on LSD.<ref>{{Cite web|title=OBITUARY — Ron Thelin |url=https://www.sfgate.com/news/article/OBITUARY-Ron-Thelin-2989153.php |vauthors=Taylor M |date=1996-03-22 |website=SFGate |access-date=2020-05-13 |url-status=live |archive-date=August 28, 2021 |archive-url=https://web.archive.org/web/20210828153344/https://www.sfgate.com/news/article/OBITUARY-Ron-Thelin-2989153.php}}</ref><ref>{{cite journal |vauthors=Davis JC |title=The business of getting high: head shops, countercultural capitalism, and the marijuana legalization movement. |journal=The Sixties |date=January 2015 |volume=8 |issue=1 |pages=27–49 |doi=10.1080/17541328.2015.1058480 |hdl=11603/7422 |s2cid=142795620 |hdl-access=free}}</ref>

A similar movement developed in London, led by British academic [[Michael Hollingshead]], who first tried LSD in America in 1961. After experiencing LSD and interacting with notable figures such as [[Aldous Huxley]], [[Timothy Leary]], and [[Richard Alpert]], Hollingshead played a key role in the famous LSD research at Millbrook before moving to New York City for his experiments. In 1965, he returned to the UK and founded the World Psychedelic Center in Chelsea, London.<ref>{{cite book | vauthors = Conners P |title=White Hand Society - The Psychedelic Partnership of Timothy Leary and Allen Ginsberg |publisher=City Lights Books |year=2010 |isbn=978-0-87286-535-8 |page=[https://archive.org/details/isbn_9780872865358/page/148 148] |url-access=registration |url=https://archive.org/details/isbn_9780872865358/page/148 }}</ref>

===Art and music===
====Art====
=====Blotter art=====
{{Main|Blotter art}}

[[File:LSD Tabs 50mcg.jpg|thumb|LSD tabs (50 mcg) featuring blotter art]]

Blotter art is an art form printed on perforated sheets of absorbent [[blotting paper]] infused with liquid LSD. The delivery method gained popularity following the banning of the [[hallucinogen]] LSD in the late 1960s. The use of graphics on blotter sheets originated as an [[underground art]] form in the early 1970s, sometimes to help identify the dose, maker, or batch of LSD.

=====LSD art=====
{{Main|LSD art}}

[[File:Lsdfacecoloured.jpg|thumb|left|A drawing of a face, made under the effects of LSD. [[Dr. Oscar Janiger]] noted similarities between paintings made under the influence of the drug and those made by schizophrenics.]]

LSD art is any [[art]] or visual displays inspired by [[psychedelic experiences]] and [[hallucination]]s known to follow the ingestion of LSD (also known colloquially as acid).<ref name="Schmid_2015">{{Cite journal | vauthors = Schmid Y, Enzler F, Gasser P, Grouzmann E, Preller KH, Vollenweider FX, Brenneisen R, Müller F, Borgwardt S | title = Acute Effects of Lysergic Acid Diethylamide in Healthy Subjects | journal = Biological Psychiatry | volume = 78 | issue = 8 | pages = 544–553 | date = 2015-10-15 | pmid = 25575620 | doi = 10.1016/j.biopsych.2014.11.015 | url = http://edoc.unibas.ch/42234/1/20160316150932_56e9691c51f97.pdf | language = English | s2cid = 31659064 | issn = 0006-3223 }}</ref> Artists and scientists have been interested in the effect of LSD on drawing and painting since it first became available for legal use and general consumption.<ref>{{cite book | vauthors = Stafford PG, Golightly BH | title = LSD — The Problem-Solving Psychedelic | url = http://www.psychedelic-library.org/staf3.htm }}</ref>

====Music====
[[File:Helix, v.2, no.6, Dec. 1, 1967 - DPLA - 85798bf5973acd2aa823cbc257dfae2a (page 1).jpg|thumb|Psychedelic art for the cover of an issue of underground [[Counterculture of the 1960s|counterculture]] newspaper ''[[Helix (newspaper)|Helix]]'', 1967.]]

The influence of LSD in the realms of music and art became pronounced in the 1960s, especially through the Acid Tests and related events involving bands like the [[Grateful Dead]], [[Jefferson Airplane]], and [[Big Brother and the Holding Company]]. San Francisco-based artists such as [[Rick Griffin]], [[Victor Moscoso]], and [[Wes Wilson]] contributed to this movement through their psychedelic poster and album art. [[The Grateful Dead]], in particular, became central to the culture of "Deadheads", with their music heavily influenced by LSD.<ref name=Jarnow/>

In the United Kingdom, Michael Hollingshead, reputed for introducing LSD to various artists and musicians like [[Storm Thorgerson]], [[Donovan]], [[Keith Richards]], and members of [[the Beatles]], played a significant role in the drug's proliferation in the British art and music scene. Despite LSD's illegal status since 1966, it was widely used by groups including [[the Beatles]], [[the Rolling Stones]], and [[the Moody Blues]]. Their experiences influenced works such as the Beatles' ''[[Sgt. Pepper's Lonely Hearts Club Band]]'' and Cream's ''[[Disraeli Gears]]'', featuring psychedelic-themed music and artwork.<ref>{{cite magazine |vauthors=Gilmore M |url=https://www.rollingstone.com/feature/beatles-acid-test-how-lsd-opened-the-door-to-revolver-251417/ |title=Beatles' Acid Test: How LSD Opened the Door to 'Revolver' |magazine=Rolling Stone |date=August 25, 2016 |access-date=December 9, 2021 |archive-date=December 3, 2020 |archive-url=https://web.archive.org/web/20201203211257/https://www.rollingstone.com/feature/beatles-acid-test-how-lsd-opened-the-door-to-revolver-251417/ |url-status=live}}</ref>

Psychedelic music of the 1960s often sought to replicate the LSD experience, incorporating exotic instrumentation, electric guitars with effects pedals, and elaborate studio techniques. Artists and bands used instruments such as sitars and tablas and employed studio effects such as backward tape, panning, and phasing.<ref>{{cite book |vauthors=Rubin R, Melnick JP |title=Immigration and American Popular Culture: an Introduction |location=New York, NY |publisher=New York University Press |date=2007 |isbn=978-0-8147-7552-3 |pages=162–4}}</ref><ref>{{cite book |vauthors=Prown P, Newquist HP, Eiche JF |title=Legends of Rock Guitar: the Essential Reference of Rock's Greatest Guitarists |location=London |publisher=Hal Leonard Corporation, 1997 |isbn=0-7935-4042-9 |page=48 |year=1997}}</ref> Songs such as [[John Prine]]'s "Illegal Smile" and the Beatles' "[[Lucy in the Sky with Diamonds]]" have been associated with LSD, although the latter's authors denied such claims.<ref name=Sheff>{{cite book |vauthors=Sheff D |year=2000 |author-link=David Sheff |title=All We Are Saying: The Last Major Interview with John Lennon and Yoko Ono |publisher=St. Martin's Press |location=New York |isbn=978-0-312-25464-3 |url=https://archive.org/details/allwearesayingla00lenn |url-access=registration}}</ref>{{page needed|date=January 2024}}<ref name="life">{{cite magazine |vauthors=Thompson T |date=16 June 1967 |title=The New Far-Out Beatles |magazine=Life |url=https://books.google.com/books?id=lVYEAAAAMBAJ&pg=101 |location=Chicago |publisher=Time Inc. |page=101 |access-date=8 Dec 2016 |archive-date=November 17, 2021 |archive-url=https://web.archive.org/web/20211117042255/https://books.google.com/books?id=lVYEAAAAMBAJ&pg=101 |url-status=live}}</ref>

Contemporary artists influenced by LSD include [[Keith Haring]] in the visual arts,<ref>{{cite book |title=Keith Haring: Journey of the Radiant Baby |url=https://books.google.com/books?id=PElY27UXXkYC |publisher=Bunker Hill Publishing |year=2006 |isbn=1-59373-052-7 |vauthors=Haring K |page=25 |access-date=December 5, 2023 |archive-date=October 2, 2023 |archive-url=https://web.archive.org/web/20231002134101/https://books.google.com/books?id=PElY27UXXkYC |url-status=live }}</ref> various [[electronic dance music]] creators,<ref>{{cite news |url=https://www.vice.com/en/article/why-drugs-genres-match-mdma-raves-shrooms-psychedelia-rap-lean/ |publisher=Vice |author=Daisy Jones |date=5 June 2017 |title=Why Certain Drugs Make Specific Genres Sound So Good |access-date=December 5, 2023 |archive-date=December 5, 2023 |archive-url=https://web.archive.org/web/20231205200458/https://www.vice.com/en/article/newv7g/why-drugs-genres-match-mdma-raves-shrooms-psychedelia-rap-lean |url-status=live }}</ref> and the [[jam band]] [[Phish]].<ref>{{cite web |url=https://liveforlivemusic.com/features/phish-matisyahu-nyc/ |title=Phishin' With Matisyahu: How LSD "Turned My Entire World Inside Out" |author=Kendall Deflin |date=22 June 2017 |access-date=December 5, 2023 |archive-date=September 30, 2023 |archive-url=https://web.archive.org/web/20230930095840/https://liveforlivemusic.com/features/phish-matisyahu-nyc/ |url-status=live }}</ref> The 2018 [[Leo Butler]] play ''[[All You Need is LSD]]'' is inspired by the author's interest in the history of LSD.<ref>{{Cite web |title=How LSD influenced Western culture |url=https://www.bbc.com/culture/article/20181016-how-lsd-influenced-western-culture |access-date=2024-01-08 |website=www.bbc.com |date=October 17, 2018 |archive-date=November 27, 2020 |archive-url=https://web.archive.org/web/20201127003729/https://www.bbc.com/culture/article/20181016-how-lsd-influenced-western-culture |url-status=live }}</ref>

===Legal status===
The [[United Nations]] [[Convention on Psychotropic Substances]] of 1971 mandates that signing parties, including the United States, Australia, New Zealand, and most of Europe, prohibit LSD. Enforcement of these laws varies by country. The convention allows medical and scientific research with LSD.<ref>{{cite web |work=UN Convention on Psychotropic Substances |date=1971 |url=http://www.unodc.org/pdf/convention_1971_en.pdf |title=Final act of the United Nations Conference |archive-url=https://web.archive.org/web/20120415011336/http://www.unodc.org/pdf/convention_1971_en.pdf |archive-date=15 April 2012}}</ref>

====Australia====
In [[Australia]], LSD is classified as a [[Standard for the Uniform Scheduling of Medicines and Poisons#Schedule 9: Prohibited Substance|Schedule 9]] [[prohibited substance]] under the [[Standard for the Uniform Scheduling of Medicines and Poisons|Poisons Standard]] (February 2017), indicating it may be abused or misused and its manufacture, possession, sale, or use should be prohibited except for approved research purposes.<ref name="Poisons Standard">{{cite web |url=https://www.legislation.gov.au/Details/F2017L00057 |title=Poisons Standard |date=July 2016 |archive-url=https://web.archive.org/web/20170302025331/https://www.legislation.gov.au/Details/F2017L00057 |archive-date=2 March 2017 |work=Therapeutic Goods Administration |publisher=Australian Government Department of Health}}</ref> In Western Australia, the Misuse of Drugs Act 1981 provides guidelines for possession and trafficking of substances like LSD.<ref>{{cite web |title=Misuse of Drugs Act 1981 |date=18 November 2015 |url=http://www.slp.wa.gov.au/pco/prod/FileStore.nsf/Documents/MRDocument:28280P/$FILE/Misuse%20Of%20Drugs%20Act%201981%20-%20%5B06-e0-00%5D.pdf?OpenElement |publisher=Government of Western Australia |archive-url=https://web.archive.org/web/20151222180141/http://www.slp.wa.gov.au/pco/prod/FileStore.nsf/Documents/MRDocument%3A28280P/%24FILE/Misuse%20Of%20Drugs%20Act%201981%20-%20%5B06-e0-00%5D.pdf?OpenElement |archive-date=22 December 2015}}</ref>

====Canada====
In [[Canada]], LSD is listed under [[Controlled Drugs and Substances Act#Schedule III|Schedule III]] of the [[Controlled Drugs and Substances Act]] (CDSA). Unauthorized possession and trafficking of the substance can lead to significant legal penalties.<ref name="cdasa">{{cite web|url=http://laws-lois.justice.gc.ca/eng/acts/C-38.8/page-26.html#h-30 |title=Controlled Drugs and Substances Act |access-date=December 15, 2013 |publisher=Canadian Department of Justice |year=1996 |author=Canadian government |website=Justice Laws |archive-url=https://web.archive.org/web/20131215170432/http://laws-lois.justice.gc.ca/eng/acts/C-38.8/page-26.html |archive-date=December 15, 2013 }}</ref>

====United Kingdom====
In the [[United Kingdom]], LSD is a [[Misuse of Drugs Act 1971#Class A drugs|Class A]] drug under the [[Misuse of Drugs Act 1971]], making unauthorized possession and trafficking punishable by severe penalties. The Runciman Report and Transform Drug Policy Foundation have made recommendations and proposals regarding the legal regulation of LSD and other psychedelics.<ref>{{cite web |url=http://www.druglibrary.org/schaffer/Library/studies/runciman/pf3.htm |title=Drugs and the law: Report of the inquiry into the Misuse of Drugs Act 1971 |archive-url=https://web.archive.org/web/20160130144204/http://www.druglibrary.org/schaffer/Library/studies/runciman/pf3.htm |archive-date=30 January 2016 |location=London |publisher=Police Foundation |date=2000 |work=[[Runciman Report]]}}</ref><ref>{{cite web |url=http://www.tdpf.org.uk/blueprint%20download.htm |title=After the War on Drugs: Blueprint for Regulation |archive-url=https://web.archive.org/web/20131005145241/http://www.tdpf.org.uk/blueprint%20download.htm |archive-date=5 October 2013 |work=Transform Drug Policy Foundation |date=2009}}</ref>

====United States====
In the [[United States]], LSD is classified as a [[Controlled Substances Act#Schedule I|Schedule I]] [[controlled substance]] under the [[Controlled Substances Act of 1970]], making its manufacture, possession, and distribution illegal without a DEA license.<ref name="OrangeBook2026">{{citation | title = Orange Book: List of Controlled Substances and Regulated Chemicals (January 2026) | date = January 2026 | publisher = U.S. [[Department of Justice]]: [[Drug Enforcement Administration]] (DEA): Diversion Control Division | location = [[United States]] | url = https://www.deadiversion.usdoj.gov/schedules/orangebook/orangebook.pdf}}</ref> The law considers LSD to have a high potential for abuse, no legitimate medical use, and to be unsafe even under medical supervision. The US Supreme Court case Neal v. United States (1995) clarified the sentencing guidelines related to LSD possession.<ref>{{cite court| litigants=Neal v. United States| reporter=U.S.| vol=516| opinion=284| pinpoint=| court=| year=1996| url=https://www.law.cornell.edu/supct/html/94-9088.ZO.html| archive-url=https://web.archive.org/web/20160409213251/https://www.law.cornell.edu/supct/html/94-9088.ZO.html| url-status=live}}, originating from U.S. v. Neal, 46 F.3d 1405 (7th Cir. 1995)</ref>

[[Oregon]] decriminalized personal possession of small amounts of drugs, including LSD, in February 2021, and [[California]] has seen legislative efforts to decriminalize psychedelics.<ref>{{Cite web|vauthors=Jaeger K|date=2021-06-29|title=California Lawmakers Approve Bill To Legalize Psychedelics Possession In Committee|url=https://www.marijuanamoment.net/california-lawmakers-approve-bill-to-legalize-psychedelics-possession-in-committee/|access-date=2021-07-08|website=Marijuana Moment|language=en-US|archive-date=July 9, 2021|archive-url=https://web.archive.org/web/20210709172122/https://www.marijuanamoment.net/california-lawmakers-approve-bill-to-legalize-psychedelics-possession-in-committee/|url-status=live}}</ref>

====Mexico====
[[Mexico]] decriminalized the possession of small amounts of drugs, including LSD, for personal use in 2009. The law specifies possession limits and establishes that possession is not a crime within designated quantities.<ref>{{cite web |url=http://www.elpensador.com.mx/2009/10/17/Ley-de-Narcomenudeo/ |title=Ley de Narcomenudeo |archive-url=https://web.archive.org/web/20101130224127/http://www.elpensador.com.mx/2009/10/17/Ley-de-Narcomenudeo/ |archive-date=30 November 2010 |language=es |work=El Pensador |date=17 October 2009}}</ref>

====Czech Republic====
In the [[Czech Republic]], possession of "amount larger than small" of LSD is criminalized, while possession of smaller amounts is a misdemeanor. The definition of "amount larger than small" is determined by judicial practice and specific regulations.<ref name="Cz expl rep">{{cite report |publisher=Parliament of the Czech Republic |year=1998 |title=Explanatory Report to Act No. 112/1998 Coll., which amends the Act No. 140/1961 Coll., the Criminal Code, and the Act No. 200/1990 Coll., on misdemeanors |location=Prague |language=cs}}</ref><ref>{{Citation |author=Supreme Court of the Czech Republic |author-link=Supreme Court of the Czech Republic |date=25 February 2012 |title=6 Tdo 156/2010 [NS 7078/2010]}}</ref>

===Illicit supply chain===
====Production====
[[File:LSDLabGlassware.jpg|thumb|Glassware seized by the DEA.]]

An active dose of LSD is very minute, allowing a large number of doses to be synthesized from a comparatively small amount of raw material. Twenty-five kilograms of precursor [[ergotamine]] [[tartrate]] can produce 5–6{{nbsp}}kg of pure crystalline LSD; this corresponds to around 50–60{{nbsp}}million doses at 100{{nbsp}}μg. Because the masses involved are so small, concealing and transporting illicit LSD is much easier than smuggling [[cocaine]], [[cannabis (drug)|cannabis]], or other illegal drugs.<ref name="DEA-pub">{{cite web|author=DEA |year=2007 |title=LSD Manufacture – Illegal LSD Production |url=https://fas.org/irp/agency/doj/dea/product/lsd/lsd-5.htm |website=LSD in the United States |publisher=U.S. Department of Justice Drug Enforcement Administration |archive-url=https://web.archive.org/web/20070829023659/https://fas.org/irp/agency/doj/dea/product/lsd/lsd-5.htm|archive-date=August 29, 2007}}</ref>

Manufacturing LSD requires laboratory equipment and experience in the field of [[organic chemistry]]. It takes two to three days to produce 30 to 100 grams of pure compound. It is believed that LSD is not usually produced in large quantities, but rather in a series of small batches. This technique minimizes the loss of precursor chemicals in case a step does not work as expected.<ref name="DEA-pub"/> Ali Altaft, the lead chemist at the [[University of Okara]], in [[Punjab, Pakistan|Punjab]], Pakistan, performed the synthesis of LSD on video.<ref>{{Cite web | vauthors = Maravelias P |date=2024-12-18 |title=Willy Myco Just Released the First-Ever Video Demonstrating How to Synthesize LSD |url=https://doubleblindmag.com/willy-myco-lsd-synthesis-in-pakistan/ |access-date=2025-02-10 |website=DoubleBlind Mag |language=en-US}}</ref>

=====Forms=====
LSD is produced in crystalline form and is then mixed with [[excipient]]s or redissolved for production in ingestible forms. Liquid solution is either distributed in small vials or, more commonly, sprayed onto or soaked into a distribution medium. Historically, LSD solutions were first sold on sugar cubes, but practical considerations{{clarification needed|date=September 2024}} forced a change to [[Tablet (pharmacy)|tablet]] form. Appearing in 1968 as an orange tablet measuring about 6{{nbsp}}mm across, "Orange Sunshine" acid was the first largely available form of LSD after its possession was made illegal. [[Tim Scully]], a prominent chemist, made some of these tablets, but said that most "Sunshine" in the USA came by way of Ronald Stark, who imported approximately thirty-five million doses from Europe.<ref name=Stafford1992>{{cite book |vauthors=Stafford P |year=1992 |title=Psychedelics Encyclopaedia |chapter=Chapter 1 – The LSD Family |page=62 |edition=3rd |publisher=Ronin Publishing |isbn=978-0-914171-51-5}}</ref>

Over some time, tablet dimensions, weight, shape and concentration of LSD evolved from large (4.5–8.1{{nbsp}}mm diameter), heavyweight (≥150{{nbsp}}μg), round, high concentration (90–350{{nbsp}}μg/tab) dose units to small (2.0–3.5{{nbsp}}mm diameter) lightweight (as low as 4.7{{nbsp}}μg/tab), variously shaped, lower concentration (12–85{{nbsp}}μg/tab, average range 30–40{{nbsp}}μg/tab) dose units. LSD tablet shapes have included cylinders, cones, stars, spacecraft, and heart shapes. The smallest tablets became known as "Microdots".<ref name=Laing2003>{{cite book |vauthors=Laing RR, Beyerstein BL, Siegel JA |year=2003 |title=Hallucinogens: A Forensic Drug Handbook |chapter=Chapter 2.2 – Forms of the Drug |chapter-url=https://books.google.com/books?id=l1DrqgobbcwC |pages=39–41 |publisher=Academic Press |isbn=978-0-12-433951-4 |access-date=May 12, 2020 |archive-date=February 2, 2021 |archive-url=https://web.archive.org/web/20210202134552/https://books.google.com/books?id=l1DrqgobbcwC |url-status=live}}</ref>

After tablets came "computer acid" or "blotter paper LSD", typically made by dipping a preprinted sheet of [[blotting paper]] into an LSD/water/alcohol solution.<ref name=Stafford1992/><ref name=Laing2003/> More than 200 types of LSD tablets have been encountered since 1969, and more than 350 blotter paper designs have been observed since 1975.<ref name=Laing2003/> About the same time as blotter paper, LSD came "Windowpane" (AKA "Clearlight"), which contained LSD inside a thin [[gelatin]] square a quarter of an inch (6{{nbsp}}mm) across.<ref name=Stafford1992/> <!-- Please do not add any street names here unless you can provide evidence for their notability and importance! Additions not referenced to a reliable source will be removed immediately. The goal of an encyclopedia is to provide a "ready reference" of key concepts, not to give an exhaustive list of every detail.--> LSD has been sold under a wide variety of often short-lived and regionally restricted street names, including Acid, Trips, Uncle Sid, Blotter, [[Lucy in the Sky with Diamonds|Lucy]], Alice and doses, as well as names that reflect the designs on the sheets of blotter paper.<ref name="erowid-faq"/><ref>{{cite web| title=Street Terms: Drugs and the Drug Trade| date=April 5, 2005| url=http://www.whitehousedrugpolicy.gov/streetterms/ByType.asp?intTypeID=6| publisher=[[Office of National Drug Control Policy]]| access-date=January 31, 2007| url-status=live| archive-url=https://web.archive.org/web/20090418031446/http://www.whitehousedrugpolicy.gov/streetTerms/ByType.asp?intTypeID=6| archive-date=April 18, 2009}}</ref> Authorities have encountered the drug in other forms—including powder or crystal, and capsule.<ref>{{cite web |author=DEA |year=2008 |title=Photo Library (page 2) |publisher=US Drug Enforcement Administration |url=http://www.usdoj.gov/dea/photo_library2.html#lsd |access-date=June 27, 2008 |archive-url=https://web.archive.org/web/20080623111640/http://www.usdoj.gov/dea/photo_library2.html |archive-date=June 23, 2008}}</ref>

======Blotters======
[[Blotter art]] designs printed on blotter paper can identify dose strengths, different batches, or makers.<ref name="Sfetcu">{{cite book | vauthors = Sfetcu N |title=Health & Drugs: Disease, Prescription & Medication |date=2014 |publisher=Nicolae Sfetcu |page=1958 |url=https://books.google.com/books?id=8jF-AwAAQBAJ&dq=acid+blotter+art&pg=PA1958 |language=en |access-date=2023-07-14 |archive-date=2023-07-14 |archive-url=https://web.archive.org/web/20230714011256/https://books.google.com.ar/books?id=8jF-AwAAQBAJ&newbks=1&newbks_redir=0&lpg=PA1958&dq=acid%20blotter%20art&pg=PA1958#v=onepage&q=acid%20blotter%20art&f=false |url-status=live }}</ref>

On the other hand, blotters without art may be considered safer by some, since there is no guarantee that the [[ink cartridge|printer ink]] used in clandestine production is edible or non-toxic for long-term exposure, and it is also possible for unscrupulous dealers to mimic reputable blotter art designs to boost sales.

{{Gallery
| title        = 
| align        =
| footer       =
| style        =
| state        =
| height       =
| width        = 400
| perrow       =
| mode         = 
| whitebg      = 
| noborder     =
| captionstyle =
| 10 strip.jpg
 | 'White on White' ('WoW') LSD blotters lack blotter art (ink)
| File:Eye_of_horus_blotter_art.jpg
 | Classic LSD blotters featuring [[blotter art]]
}}

=====Distribution=====
LSD manufacturers and traffickers in the United States can be categorized into two groups: A few large-scale producers and an equally limited number of small, clandestine chemists, consisting of independent producers who, operating on a comparatively limited scale, can be found throughout the country.<ref>{{cite book |vauthors=MacLean JR, Macdonald DC, Ogden F, Wilby E |chapter=LSD-25 and mescaline as therapeutic adjuvants. |veditors=Abramson H |title=The Use of LSD in Psychotherapy and Alcoholism |publisher=Bobbs-Merrill |location=New York |date=1967 |pages=407–426}}</ref><ref>{{cite book |vauthors=Ditman KS, Bailey JJ |chapter=Evaluating LSD as a psychotherapeutic agent |veditors=Hoffer A |title=A program for the treatment of alcoholism: LSD, malvaria, and nicotinic acid |pages=353–402}}</ref>

As a group, independent producers are of less concern to the [[Drug Enforcement Administration]] than the large-scale groups because their product reaches only local markets.<ref name="LSD: The Drug"/>

Many LSD dealers and chemists describe a religious or humanitarian purpose that motivates their illicit activity. Nicholas Schou's book ''Orange Sunshine: The Brotherhood of Eternal Love and Its Quest to Spread Peace, Love, and Acid to the World'' describes one such group, [[the Brotherhood of Eternal Love]]. The group was a major American LSD trafficking group in the late 1960s and early 1970s.<ref>{{cite book| vauthors=Schou N |title=Orange Sunshine: The Brotherhood of Eternal Love and Its Quest to Spread Peace, Love, and Acid to the World |date=2010 |publisher=Thomas Dunne Books |url=https://archive.org/details/orangesunshinebr00scho_0 |url-access=registration |isbn=978-0-312-55183-4}}</ref>

In the second half of the 20th century, dealers and chemists loosely associated with the [[Grateful Dead]] like [[Owsley Stanley]], [[Nicholas Sand]], Karen Horning, Sarah Maltzer, "Dealer McDope", and [[Leonard Pickard]] played an essential role in distributing LSD.<ref name=Jarnow>{{cite book| vauthors=Jarnow J |title=Heads: A Biography of Psychedelic America |date=2016 |publisher=Da Capo Press |isbn=978-0-306-82255-1}}</ref>

==={{anchor|N-Bomb}} Mimics===
[[File:Docpsychadelic.jpg|thumb|LSD blotter acid mimic actually containing DOC.]]
[[File:Lysergic.JPG|thumb|Different blotters which could possibly be mimics.]]

Since 2005, law enforcement in the United States and elsewhere has seized several chemicals and combinations of chemicals in blotter paper which were sold as LSD mimics, including [[2,5-dimethoxy-4-bromoamphetamine|DOB]],<ref name="microgram october 2005">{{Cite journal |journal=Microgram Bulletin |date=October 2005 |author=United States Drug Enforcement Administration |volume=38 |issue=10 |url=http://www.justice.gov/dea/pr/micrograms/2005/mg1005.pdf |title=LSD Blotter Acid Mimic Containing 4-Bromo-2,5-dimethoxy-amphetamine (DOB) Seized Near Burns, Oregon |access-date=August 20, 2009 |archive-url=https://web.archive.org/web/20121018052304/http://www.justice.gov/dea/pr/micrograms/2005/mg1005.pdf |archive-date=October 18, 2012}}</ref><ref name="microgram november 2006">{{Cite journal |journal=Microgram Bulletin |date=November 2006 |volume=39 |issue=11 |author=United States Drug Enforcement Administration |page=136 |title=Intelligence Alert – Blotter Acid Mimics (Containing 4-Bromo-2,5-Dimethoxy-Amphetamine (DOB)) in Concord, California |url=http://www.justice.gov/dea/pr/micrograms/2006/mg1106.pdf |access-date=August 20, 2009 |archive-url=https://web.archive.org/web/20121018052155/http://www.justice.gov/dea/pr/micrograms/2006/mg1106.pdf |archive-date=October 18, 2012}}</ref> a mixture of [[2,5-Dimethoxy-4-chloroamphetamine|DOC]] and [[2,5-dimethoxy-4-iodoamphetamine|DOI]],<ref name="microgram march 2008">{{Cite journal |journal=Microgram Bulletin |date=March 2008 |volume=41 |issue=3 |author=United States Drug Enforcement Administration |url=http://www.justice.gov/dea/pr/micrograms/2008/mg0308.pdf |title=Unusual "Rice Krispie Treat"-Like Balls Containing Psilocybe Mushroom Parts in Warren County, Missouri |access-date=August 20, 2009 |archive-url=https://web.archive.org/web/20121017234315/http://www.justice.gov/dea/pr/micrograms/2008/mg0308.pdf |archive-date=October 17, 2012}}</ref> [[25I-NBOMe]],<ref name="ACMD Report">{{cite web| vauthors=Iversen L |title=Temporary Class Drug Order Report on 5-6APB and NBOMe compounds |url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/204808/J_TCDO_report_on_5-6APB_and_NBOMe_compounds.pdf |website=Advisory Council on the Misuse of Drugs |publisher=Gov.Uk |access-date=June 16, 2013 |date=May 29, 2013 |page=14 |url-status=live |archive-url=https://web.archive.org/web/20130921234700/https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/204808/J_TCDO_report_on_5-6APB_and_NBOMe_compounds.pdf|archive-date=September 21, 2013}}</ref> and a mixture of [[2,5-Dimethoxy-4-chloroamphetamine|DOC]] and [[2,5-dimethoxy-4-bromoamphetamine|DOB]].<ref name="microgram march 2009">{{Cite journal |journal=Microgram Bulletin |date=March 2009 |volume=42 |issue=3 |author=United States Drug Enforcement Administration |url=http://www.justice.gov/dea/pr/micrograms/2009/mg0309.pdf |title="Spice" – Plant Material(s) Laced With Synthetic Cannabinoids or Cannabinoid Mimicking Compounds |access-date=August 20, 2009 |archive-url=https://web.archive.org/web/20120118165818/http://www.justice.gov/dea/programs/forensicsci/microgram/mg0309/mg0309.html |archive-date=January 18, 2012}}</ref> Many mimics are toxic in comparatively small doses, or have extremely different safety profiles. Many street users of LSD are often under the impression that blotter paper, which is actively hallucinogenic, can only be LSD because that is the only chemical with low enough doses to fit on a small square of blotter paper. While it is true that LSD requires lower doses than most other hallucinogens, blotter paper is capable of absorbing a much larger amount of material. The DEA performed a [[chromatographic]] analysis of blotter paper containing [[2C-C]] which showed that the paper contained a much greater concentration of the active chemical than typical LSD doses, although the exact quantity was not determined.<ref name="microgram november 2005">{{Cite journal |journal=Microgram Bulletin |date=November 2005 |volume=38 |issue=11 |author=United States Drug Enforcement Administration |url=http://www.justice.gov/dea/pr/micrograms/2005/mg1105.pdf |title=Bulk Marijuana in Hazardous Packaging in Chicago, Illinois |access-date=August 20, 2009 |archive-url=https://web.archive.org/web/20121018052300/http://www.justice.gov/dea/pr/micrograms/2005/mg1105.pdf |archive-date=October 18, 2012}}</ref> Blotter LSD mimics can have relatively small dose squares; a sample of blotter paper containing [[2,5-Dimethoxy-4-chloroamphetamine|DOC]] seized by [[Concord, California]] police had dose markings approximately 6{{nbsp}}mm apart.<ref name="microgram december 2007">{{Cite journal |journal=Microgram Bulletin |date=December 2007 |volume=40 |issue=12 |author=United States Drug Enforcement Administration |url=http://www.justice.gov/dea/pr/micrograms/2007/mg1207.pdf |title=SMALL HEROIN DISKS NEAR GREENSBORO, GEORGIA |access-date=August 20, 2009 |archive-url=https://web.archive.org/web/20121017234332/http://www.justice.gov/dea/pr/micrograms/2007/mg1207.pdf |archive-date=October 17, 2012}}</ref> Several deaths have been attributed to 25I-NBOMe.<ref name="Erowid25I-NBOMe">{{cite web |url=https://www.erowid.org/chemicals/2ci_nbome/2ci_nbome_death.shtml |title=25I-NBOMe (2C-I-NBOMe) Fatalities / Deaths |publisher=Erowid |access-date=February 28, 2016 |author=Erowid |url-status=live |archive-url=https://web.archive.org/web/20160305193143/https://www.erowid.org/chemicals/2ci_nbome/2ci_nbome_death.shtml |archive-date=March 5, 2016}}</ref><ref name="NY Daily news">{{cite news| vauthors=Hastings D |title=New drug N-bomb hits the street, terrifying parents, troubling cops |url=http://www.nydailynews.com/news/national/new-synthetic-hallucinogen-n-bomb-killing-users-cops-article-1.1336327 |access-date=May 7, 2013 |newspaper=New York Daily News |date=May 6, 2013 |url-status=live|archive-url=https://web.archive.org/web/20130510103039/http://www.nydailynews.com/news/national/new-synthetic-hallucinogen-n-bomb-killing-users-cops-article-1.1336327|archive-date=May 10, 2013}}</ref><ref name="Ireland injuries">{{cite news|vauthors=Feehan C |title=Powerful N-Bomb drug – responsible for spate of deaths internationally – responsible for hospitalisation of six in Cork |url=http://www.independent.ie/irish-news/powerful-nbomb-drug-responsible-for-spate-of-deaths-internationally-responsible-for-hospitalisation-of-six-in-cork-34384507.html|access-date=January 22, 2016|newspaper=Irish Independent|date=January 21, 2016 |archive-date=April 12, 2019|archive-url=https://web.archive.org/web/20190412203933/https://www.independent.ie/irish-news/powerful-nbomb-drug-responsible-for-spate-of-deaths-internationally-responsible-for-hospitalisation-of-six-in-cork-34384507.html|url-status=live}}</ref><ref name="ACMD Report2">{{cite web |vauthors=Iversen L |title=Temporary Class Drug Order Report on 5-6APB and NBOMe compounds |url=https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/204808/J_TCDO_report_on_5-6APB_and_NBOMe_compounds.pdf |website=Advisory Council on the Misuse of Drugs |publisher=Gov.Uk |access-date=June 16, 2013 |date=May 29, 2013 |url-status=live |archive-url=https://web.archive.org/web/20130921234700/https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/204808/J_TCDO_report_on_5-6APB_and_NBOMe_compounds.pdf |archive-date=September 21, 2013}}</ref>

===Notable individuals===
Some notable individuals have commented publicly on their experiences with LSD.<ref>{{cite web |title=Famous LSD users |url=http://www.thegooddrugsguide.com/articles/famous_users/lsd.htm |publisher=The Good Drugs Guide |access-date=2008-10-20 |url-status=live |archive-url=https://web.archive.org/web/20081007023344/http://www.thegooddrugsguide.com/articles/famous_users/lsd.htm |archive-date=October 7, 2008}}</ref><ref>{{cite web |url=http://popwiki.net |title=People on psychedelics |access-date=2012-11-01 |url-status=live |archive-url=https://web.archive.org/web/20130421145334/http://popwiki.net/ |archive-date=April 21, 2013}}</ref> Some of these comments date from the era when it was legally available in the US and Europe for non-medical uses. Others pertain to [[psychiatric]] treatment in the 1950s and 1960s. Still others describe experiences with illegal LSD, obtained for philosophic, artistic, therapeutic, spiritual, or recreational purposes.

* [[W. H. Auden]], the poet, said, "I myself have taken mescaline once and L.S.D. once.  Aside from a slight schizophrenic dissociation of the I from the Not-I, including my body, nothing happened at all."<ref>{{cite journal | vauthors = Mason D | title = Review: Awe for Auden | journal = The Hudson Review | volume = 68 | issue = 3 | date = Autumn 2015 | pages = 492–500 | publisher = The Hudson Review, Inc. }}</ref> He also said, "LSD was a complete frost. … What it does seem to destroy is the power of communication. I have listened to tapes done by highly articulate people under LSD, for example, and they talk absolute drivel. They may have seen something interesting, but they certainly lose either the power or the wish to communicate."<ref>{{cite web | url = http://www.swarthmore.edu/library/auden/QandA_pt6.html | vauthors = Auden WH | title = W. H. Auden at Swathmore; An hour of questions and answers with Auden | date = 15 November 1971 | work = Exhibition notes from the W.H. Auden Collection | publisher = the Swarthmore College Library | access-date = February 23, 2021 | archive-date = June 11, 2021 | archive-url = https://web.archive.org/web/20210611212901/http://www.swarthmore.edu/library/auden/QandA_pt6.html | url-status = live }}</ref> He also said, "Nothing much happened but I did get the distinct impression that some birds were trying to communicate with me."<ref>{{cite news | url = https://www.irishtimes.com/news/a-master-of-memorable-speech-1.1195982 | vauthors = MacMonagle N | title = A Master of Memorable speech | newspaper = The Irish Times | date = 17 February 2007 }}</ref>
* [[James Cameron]], the Canadian filmmaker, has said he experimented with LSD during his college years.<ref>{{Cite web |date=2010-01-10 |title=The Impossible Reality of James Cameron |url=https://rollingstoneindia.com/james-cameron/ |access-date=2025-03-24 |website=Rolling Stone India |language=en-US}}</ref>
* [[Daniel Ellsberg]], an American peace activist, says he has had several hundred experiences with psychedelics.<ref>{{Cite web| vauthors=Meyer A |date=2022-01-24 |title=Daniel Ellsberg Talks Psychedelics, Consciousness and World Peace |url=https://www.lucid.news/daniel-ellsberg-talks-psychedelics-consciousness-and-world-peace/|access-date=2022-01-29|website=Lucid News|language=en-US|archive-date=January 29, 2022|archive-url=https://web.archive.org/web/20220129143452/https://www.lucid.news/daniel-ellsberg-talks-psychedelics-consciousness-and-world-peace/|url-status=live}}</ref>
* [[Richard Feynman]], a notable physicist at [[California Institute of Technology]], tried LSD during his professorship at Caltech. Feynman largely sidestepped the issue when dictating his anecdotes; he mentions it in passing in the "O Americano, Outra Vez" section.<ref>{{cite book | vauthors = Feynman RP |title=Surely You're Joking, Mr. Feynman!: Adventures of a Curious Character | veditors = Leighton R |publisher=[[W. W. Norton]] |year=1985 |isbn=978-0-393-01921-6 |oclc=10925248|title-link=Surely You're Joking, Mr. Feynman! }}</ref><ref>{{cite book | vauthors = Gleick J |author-link=James Gleick |title=Genius: The Life and Science of Richard Feynman |publisher=[[Pantheon Books]] |year=1992|isbn=978-0-679-40836-9 |oclc=243743850}}</ref>
* [[Jerry Garcia]] stated in a July 3, 1989 interview for ''[[Relix Magazine]]'', in response to the question "Have your feelings about LSD changed over the years?" "They haven't changed much. My feelings about LSD are mixed. It's something that I both fear and that I love at the same time. I never take any psychedelic, have a psychedelic experience, without having that feeling of, "I don't know what's going to happen." In that sense, it's still fundamentally an enigma and a mystery."<ref>{{cite web|url=http://www.relix.com/features/2010/04/20/q-a-with-jerry-garcia-portrait-of-an-artist-as-a-tripper?3 |title=Q&A with Jerry Garcia: Portrait of an Artist as a Tripper |publisher=Relix Magazine |date=April 20, 2010 |access-date=2013-06-29 | vauthors = Alderson J |archive-url=https://web.archive.org/web/20100521033451/http://www.relix.com/features/2010/04/20/q-a-with-jerry-garcia-portrait-of-an-artist-as-a-tripper?3 |archive-date=May 21, 2010}}</ref>
* [[Bill Gates]] implied in an interview with ''[[Playboy]]'' that he tried LSD during his youth.<ref>{{cite magazine |title= The Bill Gates Interview |magazine= Playboy |date= July 1994 |url= http://www.playboy.com/playground/view/50-years-of-the-playboy-interview-bill-gates |archive-url= https://web.archive.org/web/20140707190401/http://www.playboy.com/playground/view/50-years-of-the-playboy-interview-bill-gates |archive-date= July 7, 2014}}</ref>
* [[Aldous Huxley]], author of ''[[Brave New World]]'', became a user of psychedelics after moving to [[Hollywood, Los Angeles|Hollywood]]. He was at the forefront of the counterculture's use of psychedelic drugs, which led to his 1954 work ''[[The Doors of Perception]]''. Dying from cancer, he asked his wife on 22 November 1963 to inject him with 100{{nbsp}}μg of LSD. He died later that day.<ref name=OpenCulture>{{cite news |vauthors=Colman D |title=Aldous Huxley's LSD Death Trip |newspaper=Open Culture |date=October 2011 |url=http://www.openculture.com/2011/10/aldous_huxleys_lsd_death_trip.html |access-date=1 November 2011 |url-status=live |archive-url=https://web.archive.org/web/20111112140024/http://www.openculture.com/2011/10/aldous_huxleys_lsd_death_trip.html |archive-date=November 12, 2011}}</ref>
* [[Steve Jobs]], co-founder and former CEO of [[Apple Inc.]], said, "Taking LSD was a profound experience, one of the most important things in my life."<ref>{{Cite news | vauthors = Bosker B |title=The Steve Jobs Reading List: The Books And Artists That Made The Man |newspaper=Huffington Post |url=http://www.huffingtonpost.com/2011/10/21/the-steve-jobs-reading-list-the-books_n_1024021.html |access-date=23 October 2011 |date=21 October 2011 |url-status=live |archive-url=https://web.archive.org/web/20111022123850/http://www.huffingtonpost.com/2011/10/21/the-steve-jobs-reading-list-the-books_n_1024021.html |archive-date=October 22, 2011}}</ref>
* [[Ernst Jünger]], German writer and philosopher, throughout his life had experimented with [[Psychoactive drug|drugs]] such as [[diethyl ether|ether]], [[cocaine]], and [[hashish]]; and later in life he used [[mescaline]] and LSD. These experiments were recorded comprehensively in ''Annäherungen'' (1970, ''Approaches''). The novel ''[[Besuch auf Godenholm]]'' (1952, ''Visit to Godenholm'') is clearly influenced by his early experiments with mescaline and LSD. He met with LSD inventor [[Albert Hofmann]] and they took LSD together several times. Hofmann's memoir ''LSD, My Problem Child'' describes some of these meetings.<ref>{{cite web|title=LSD, My Problem Child · Radiance from Ernst Junger|website=www.psychedelic-library.org |url=http://www.psychedelic-library.org/child7.htm |access-date=April 17, 2021|archive-date=May 12, 2021|archive-url=https://web.archive.org/web/20210512173700/http://www.psychedelic-library.org/child7.htm|url-status=live}}</ref>
* In a 2004 interview, [[Paul McCartney]] said that [[The Beatles]]' songs "[[Day Tripper]]" and "[[Lucy in the Sky with Diamonds]]" were inspired by LSD trips.<ref name=Sheff/>{{rp|182}} Nonetheless, [[John Lennon]] consistently stated over the course of many years that the fact that the initials of "Lucy in the Sky with Diamonds" spelled out L-S-D was a coincidence (he stated that the title came from a picture drawn by his son [[Julian Lennon|Julian]]) and that the band members did not notice until after the song had been released, and Paul McCartney corroborated that story.<ref>{{cite web |date=1998-02-15 |title=Is 'Lucy in the Sky with Diamonds' Code for LSD? |url=https://www.snopes.com/fact-check/lucy-in-the-sky-with-diamonds/ |access-date=2012-06-20 |website=Snopes.com |publisher= |archive-date=December 20, 2021 |archive-url=https://web.archive.org/web/20211220152957/https://www.snopes.com/fact-check/lucy-in-the-sky-with-diamonds/ |url-status=live }}</ref> [[John Lennon]], [[George Harrison]], and [[Ringo Starr]] also used the drug, although McCartney cautioned that "it's easy to overestimate the influence of drugs on the Beatles' music."<ref name="weeklystandard">{{cite magazine |title=The Truth Behind "LSD" |vauthors=Matus V |date=June 2004 |magazine=The Weekly Standard |url=https://www.washingtonexaminer.com/weekly-standard/the-truth-behind-lsd |access-date=November 3, 2019 |url-status=live |archive-date=March 8, 2021 |archive-url=https://web.archive.org/web/20210308185326/https://www.washingtonexaminer.com/weekly-standard/the-truth-behind-lsd}}</ref>
*[[Michel Foucault]] had an LSD experience with Simeon Wade in [[Death Valley]] and later wrote "it was the greatest experience of his life, and that it profoundly changed his life and his work."<ref>{{Cite web|url=http://www.openculture.com/2017/09/when-michel-foucault-tripped-on-acid-in-death-valley-and-called-it-the-greatest-experience-of-my-life-1975.html|title=When Michel Foucault Tripped on Acid in Death Valley and Called It "The Greatest Experience of My Life"|date=September 1975|website=Open Culture|language=en-US|access-date=2019-04-27|archive-date=March 15, 2021|archive-url=https://web.archive.org/web/20210315225234/https://openculture.com/2017/09/when-michel-foucault-tripped-on-acid-in-death-valley-and-called-it-the-greatest-experience-of-my-life-1975.html|url-status=live}}</ref><ref>{{Cite news |url=https://lareviewofbooks.org/article/blowing-the-philosophers-fuses-michel-foucaults-lsd-trip-in-the-valley-of-death/|title=Blowing The Philosopher's Fuses: Michel Foucault's LSD Trip in The Valley of Death|vauthors=Penner J|website=Los Angeles Review of Books|date=June 17, 2019 |language=en-US|access-date=11 April 2021|archive-date=April 11, 2021|archive-url=https://web.archive.org/web/20210411165642/https://lareviewofbooks.org/article/blowing-the-philosophers-fuses-michel-foucaults-lsd-trip-in-the-valley-of-death/#_ftnref4|url-status=live}} Wade: "We fell silent to listen to Stockhausen's ''[[Gesang der Jünglinge|Songs of Youth]]''. Zabriskie Point was filled with the sound of a kindergarten playground overlaid with electric tonalities. ''Kontakte'' followed. [[Glissando]]s bounced off the stars, which glowed like incandescent pinballs. Foucault turned to Michael and said, "This is the first time he really understood what Stockhausen had achieved".</ref> According to Wade, as soon as he came back to Paris, Foucault scrapped the second History of Sexuality's manuscript, and totally rethought the whole project.<ref>{{Cite book|title=Foucault in California: [A True Story-–Wherein the Great French Philosopher Drops Acid in the Valley of Death]| vauthors=Wade S |publisher=Heyday Books |year=2019 |isbn=978-1-59714-463-6}} In a letter to Wade, dated 16 September 1978, Foucault authorised the book's publication and added: "How could I not love you?"</ref>
* [[Kary Mullis]] is reported to credit LSD with helping him develop [[Polymerase chain reaction|DNA amplification]] technology, for which he received the [[Nobel Prize in Chemistry]] in 1993.<ref>{{Cite magazine| url=https://www.wired.com/science/discoveries/news/2006/01/70015 |title=LSD: The Geek's Wonder Drug? |access-date=2008-03-11 |vauthors=Harrison A |date=2006-01-16 |magazine=Wired |quote=Like Herbert, many scientists and engineers also report heightened states of creativity while using LSD. During a press conference on Friday, Hofmann revealed that he was told by Nobel-prize-winning chemist Kary Mullis that LSD had helped him develop the polymerase chain reaction that helps amplify specific DNA sequences. |url-status=live |archive-url=https://web.archive.org/web/20080505100508/http://www.wired.com/science/discoveries/news/2006/01/70015 |archive-date=May 5, 2008}}</ref>
* [[Carlo Rovelli]], an Italian [[theoretical physicist]] and writer, has credited his use of LSD with sparking his interest in theoretical physics.<ref>{{Cite web|vauthors=Higgins C|date=2018-04-14|title='There is no such thing as past or future': physicist Carlo Rovelli on changing how we think about time |website=The Guardian |url=http://www.theguardian.com/books/2018/apr/14/carlo-rovelli-exploding-commonsense-notions-order-of-time-interview |access-date=2022-02-06|archive-date=January 11, 2022|archive-url=https://web.archive.org/web/20220111094136/https://www.theguardian.com/books/2018/apr/14/carlo-rovelli-exploding-commonsense-notions-order-of-time-interview|url-status=live}}</ref>
* [[Oliver Sacks]], a [[neurologist]] famous for writing best-selling case histories about his patients' disorders and unusual experiences, talks about his own experiences with LSD and other perception altering chemicals, in his book, ''[[Hallucinations (book)|Hallucinations]]''.<ref>{{cite book |vauthors=Sacks O |date=2012 |title=Hallucinations |publisher=[[Vintage Books]] |page=106 |url=https://www.oliversacks.com/books-by-oliver-sacks/hallucinations/ |isbn=978-0-307-94743-7 |quote=On the West Coast in the early 1960s LSD and morning glory seeds were readily available, so I sampled those, too. |access-date=June 30, 2018 |url-status=live |archive-date=April 21, 2021 |archive-url=https://web.archive.org/web/20210421064209/https://www.oliversacks.com/books-by-oliver-sacks/hallucinations/}}</ref>
* [[Alexander Shulgin]], American chemist, told Albert Hofmann that he preferred LSD to [[2C-B]].
* [[Matt Stone]] and [[Trey Parker]], creators of the TV series ''[[South Park]]'', claimed to have shown up at the [[72nd Academy Awards]], at which they were nominated for Best Original Song, under the influence of LSD.<ref>{{cite web | vauthors = Bose SD |title=When Trey Parker and Matt Stone went to the Oscars on LSD Swapnil Dhruv Bose |date=December 27, 2021 |website=FarOutMagazine.co.uk |url=https://faroutmagazine.co.uk/when-trey-parker-and-matt-stone-went-to-the-oscars-on-lsd/ |access-date=January 20, 2022 |url-status=live |archive-date=January 20, 2022 |archive-url=https://web.archive.org/web/20220120001258/https://faroutmagazine.co.uk/when-trey-parker-and-matt-stone-went-to-the-oscars-on-lsd/}}</ref>

==Research==
===Psychiatric disorders===
{{See also|Psychedelic therapy|List of investigational hallucinogens and entactogens}}

LSD was initially explored for [[psychiatry|psychiatric]] use due to its structural similarity to the [[neurotransmitter]] [[serotonin]] and its [[drug safety|safety]] profile.<ref name="Nichols2018a" /> In the 1950s and 1960s, it was used in psychiatry to enhance [[psychotherapy]], known as [[psychedelic therapy]]. In the [[United States]], the earliest research began in the 1950s. [[Albert Kurland]] and his colleagues published research on LSD's therapeutic potential to treat [[schizophrenia]]. In [[Canada]], [[Humphry Osmond]] and [[Abram Hoffer]] completed LSD studies as early as 1952.<ref>{{Cite journal | vauthors = Dyck E |date=1965 |title=Flashback: Psychiatric Experimentation with LSD in Historical Perspective. |journal=Canadian Journal of Psychiatry |volume=50 |issue=7}}</ref> Some [[psychiatrist]]s, such as [[Ronald A. Sandison]], who pioneered its use at [[Powick Hospital]] in England, believed that LSD was especially useful at helping patients to "unblock" repressed subconscious material through other [[psychotherapeutic]] methods,<ref name="Cohen1959">Cohen, S. (1959). "The therapeutic potential of LSD-25". ''A Pharmacologic Approach to the Study of the Mind'', p. 251–258.</ref> and also for treating [[alcoholism]].<ref>{{cite journal |title=Use of d-Lysergic Acid Diethylamide in the Treatment of Alcoholism |journal=Q. J. Stud. Alcohol |volume=20 |pages=577–590 |vauthors=Chwelos N, Blewett DB, Smith CM, Hoffer A |date=1959 |issue=3 |doi=10.15288/qjsa.1959.20.577 |pmid=13810249 |url=http://www.erowid.org/references/texts/show/1852docid1733 |access-date=June 20, 2012 |archive-url=https://web.archive.org/web/20210224135151/https://www.erowid.org/references/texts/show/1852docid1733 |archive-date=February 24, 2021 |url-status=live}} Via {{cite web |title=Abstract |url=http://www.hofmann.org/papers/blewett_1.html |access-date=February 22, 2012 |url-status=live |archive-url=https://web.archive.org/web/20120203022019/http://www.hofmann.org/papers/blewett_1.html |archive-date=February 3, 2012 |website=Hofmann.org}}</ref><ref>{{Cite journal |vauthors=Frood A |date=2012-03-09 |title=LSD helps to treat alcoholism |journal=Nature News |url=http://www.nature.com/news/lsd-helps-to-treat-alcoholism-1.10200 |doi=10.1038/nature.2012.10200 |s2cid=137367650 |access-date=December 25, 2020 |archive-date=March 8, 2021 |archive-url=https://web.archive.org/web/20210308135250/https://www.nature.com/news/lsd-helps-to-treat-alcoholism-1.10200 |url-status=live}}</ref> One study concluded, "The root of the therapeutic value of the LSD experience is its potential for producing [[self-acceptance]] and self-surrender,"<ref name="Use of d-lysergic acid diethylamide"/> presumably by forcing the user to face issues and problems in that individual's psyche. By the 1960s, however, controversies surrounding "[[hippie]]" [[counterculture]] began to deplete institutional support for continued study.

In 2001, the United States [[Drug Enforcement Administration]] (DEA) stated that LSD "produces no [[aphrodisiac]] effects, does not increase [[creativity]], has no lasting positive effect in treating [[alcoholics]] or [[criminality|criminal]]s, does not produce a "[[model psychosis]]", and does not generate immediate personality change."<ref name="LSD: The Drug"/>

In more recent years, there has been renewed clinical research on and interest in LSD for potential therapeutic uses.<ref name="new research"/> This has been supported by several organizations, including the [[Multidisciplinary Association for Psychedelic Studies]] (MAPS), the [[Beckley Foundation]], the [[Heffter Research Institute]], and the Albert Hofmann Foundation, which exist to fund, encourage, and coordinate research into the medicinal and spiritual uses of LSD and related psychedelics.<ref>{{cite web |url=http://www.hofmann.org/ |title=The Albert Hofmann Foundation |access-date=September 27, 2007 |website=Hofmann Foundation |archive-url=https://web.archive.org/web/20190719174636/http://www.hofmann.org/ |archive-date=July 19, 2019}}</ref> 

New clinical LSD experiments in humans started in 2009 for the first time in 35 years.<ref name="new research">{{cite web|title=LSD-Assisted Psychotherapy |website=MAPS |url=http://www.maps.org/research/psilo-lsd |access-date=October 16, 2013|url-status=deviated |archive-url=https://web.archive.org/web/20180511060129/http://www.maps.org/research/psilo-lsd|archive-date=May 11, 2018}}</ref> As the drug is illegal in many areas of the world, potential medical uses have historically been difficult to study.<ref name="Nutt2009" /> Investigational uses of LSD include the treatment of [[alcoholism]],<ref name=":0">{{cite journal |vauthors=Bogenschutz MP |date=March 2013 |title=Studying the effects of classic hallucinogens in the treatment of alcoholism: rationale, methodology, and current research with psilocybin |journal=Current Drug Abuse Reviews |volume=6 |issue=1 |pages=17–29 |pmid=23627783 |doi=10.2174/15733998113099990002}}</ref> [[anxiety]], and [[depression (mood)|depression]], among other conditions.<ref>{{Cite journal |title=LSD Therapy for Persons Suffering From Major Depression - Full Text View |url=https://clinicaltrials.gov/ct2/show/NCT03866252 |access-date=2021-03-09 |website=ClinicalTrials.gov |date=February 8, 2021 |language=en |archive-date=June 11, 2021 |archive-url=https://web.archive.org/web/20210611214216/https://clinicaltrials.gov/ct2/show/NCT03866252 |url-status=live}}</ref><ref name=":5">{{Cite news |vauthors=Lustberg D |date=2022-10-14 |title=Acid for Anxiety: Fast and Lasting Anxiolytic Effects of LSD |url=https://psychedelicreview.com/acid-for-anxiety-fast-and-lasting-anxiolytic-effects-of-lsd/ |access-date=2022-12-01 |website=Psychedelic Science Review |language=en-US |archive-date=December 1, 2022 |archive-url=https://web.archive.org/web/20221201092629/https://psychedelicreview.com/acid-for-anxiety-fast-and-lasting-anxiolytic-effects-of-lsd/ |url-status=live }}</ref><ref name=":6">{{cite journal | vauthors = Holze F, Gasser P, Müller F, Dolder PC, Liechti ME | date = September 2022 | title = Lysergic Acid Diethylamide-Assisted Therapy in Patients With Anxiety With and Without a Life-Threatening Illness: A Randomized, Double-Blind, Placebo-Controlled Phase II Study | journal = Biological Psychiatry | volume = 93 | issue = 3 | pages = 215–223 | doi = 10.1016/j.biopsych.2022.08.025 | pmid = 36266118 | s2cid = 252095586 | doi-access = free }}</ref><ref name="clinicalLSD">{{cite journal |vauthors=Liechti ME |title=Modern Clinical Research on LSD |journal=Neuropsychopharmacology |volume=42 |issue=11 |pages=2114–2127 |date=October 2017 |pmid=28447622 |pmc=5603820 |doi=10.1038/npp.2017.86}}</ref><ref>{{Cite news |title=Psychedelics are transforming the way we understand depression and its treatment |date=April 20, 2021 |newspaper=The Guardian |vauthors=Carhart-Harris R |url=https://www.theguardian.com/commentisfree/2021/apr/20/psychedelics-depression-treatment-psychiatry-psilocybin |access-date=16 May 2021 |archive-url=https://web.archive.org/web/20210611212734/https://www.theguardian.com/commentisfree/2021/apr/20/psychedelics-depression-treatment-psychiatry-psilocybin|archive-date=June 11, 2021|url-status=live}}</ref> Another use is alleviation of anxiety in [[terminally ill]] [[cancer]] patients.<ref name=":5" /><ref name="new research" /><ref>{{Cite news |url=http://bazonline.ch/wissen/medizin-und-psychologie/Psychiater-Gasser-bricht-sein-Schweigen/story/25732295|title=Psychiater Gasser bricht sein Schweigen|date=July 28, 2009 |newspaper=Basler Zeitung|access-date=June 19, 2011|archive-url=https://web.archive.org/web/20111006122541/http://bazonline.ch/wissen/medizin-und-psychologie/Psychiater-Gasser-bricht-sein-Schweigen/story/25732295|archive-date=October 6, 2011}}</ref> A single dose of LSD may temporarily reduce [[alcohol abuse]] and some psychiatric symptoms, but evidence is limited and unreliable due to methodological flaws and unclear causation.<ref name="Lysergic acid diethylamide LSD fo"/><ref>{{cite journal |vauthors=Vollenweider FX, Kometer M |title=The neurobiology of psychedelic drugs: implications for the treatment of mood disorders |journal=Nature Reviews. Neuroscience |volume=11 |issue=9 |pages=642–51 |date=September 2010 |pmid=20717121 |doi=10.1038/nrn2884 |s2cid=16588263}}</ref><ref>{{cite journal |vauthors=Baumeister D, Barnes G, Giaroli G, Tracy D |title=Classical hallucinogens as antidepressants? A review of pharmacodynamics and putative clinical roles |journal=Therapeutic Advances in Psychopharmacology |volume=4 |issue=4 |pages=156–69 |date=August 2014 |pmid= 25083275 |pmc=4104707 |doi=10.1177/2045125314527985}}</ref><ref>{{cite journal |title=Therapeutic Use of LSD in Psychiatry: A Systematic Review of Randomized-Controlled Clinical Trials |vauthors=Fuentes JJ, Fonseca F, Elices M, Farré M, Torrens M |pmid=32038315 |pmc=6985449 |journal=Frontiers in Psychiatry |doi=10.3389/fpsyt.2019.00943 |volume=10 |date=January 2020 |article-number=943 |doi-access=free}}</ref>

In 2024, the FDA designated a form of LSD as a [[breakthrough therapy]] to treat [[generalized anxiety disorder]] which is being developed by [[MindMed Inc.|MindMed]].<ref name="webmd.com"/> A study published by the [[JAMA|Journal of the American Medical Association]] in September, 2025 explored the optimal dose of LSD to lower patients' anxiety.<ref name="RobisonBarrowConant2025">{{cite journal | vauthors = Robison R, Barrow R, Conant C, Foster E, Freedman JM, Jacobsen PL, Jemison J, Karas SM, Karlin DR, Solomon TM, Halperin Wernli M, Fava M | title = Single Treatment With MM120 (Lysergide) in Generalized Anxiety Disorder: A Randomized Clinical Trial | journal = JAMA | volume = 334| issue = 15| pages = 1358–1372| date = September 2025 | pmid = 40906494 | doi = 10.1001/jama.2025.13481 | pmc = 12412041 | url = }}</ref> The study was conducted by the [[pharmaceutical company]] [[MindMed]].<ref name="RobisonBarrowConant2025" /> The researchers compared how LSD doses of 25{{nbsp}}μg, 50{{nbsp}}μg, 100{{nbsp}}μg, 200{{nbsp}}μg, or [[placebo]] impacted [[Hamilton Anxiety Rating Scale|anxiety scores]] among study participants.<ref name="RobisonBarrowConant2025" /> The results of the study found that 100{{nbsp}}μg was the optimal dose to reduce anxiety among the studied patients.<ref name="RobisonBarrowConant2025" /><ref name="Perrone2025">{{Cite web | vauthors = Perrone M |date=September 4, 2025 |title=LSD shows promise for reducing anxiety in drugmaker's midstage study |url=https://apnews.com/article/lsd-psychedelics-study-anxiety-fda-drugs-trump-8821f7f3683051506d47864db5e5edcf |access-date=September 4, 2025 |website=Associated Press}}</ref>

LSD is a [[psychoplastogen]], a compound capable of promoting rapid and sustained [[neural plasticity]], an action that hypothetically might be involved in its therapeutic benefits. More research is needed to substantiate such notions.<ref name=Ly2018>{{cite journal |title=Psychedelics promote structural and functional neural plasticity |journal=Cell Reports |vauthors=Ly C, Greb AC, Cameron LP, Wong JM, Barragan EV, Wilson PC, Burbach KF, Soltanzadeh Zarandi S, Sood A, Paddy MR, Duim WC, Dennis MY, McAllister AK, Ori-McKenney KM, Gray JA, Olson DE |year=2018 |volume=23 |issue=11 |pages=3170–3182 |doi=10.1016/j.celrep.2018.05.022 |pmid=29898390 |pmc=6082376 }}</ref><ref name="pmid36123427">{{cite journal |vauthors=Calder AE, Hasler G |title=Towards an understanding of psychedelic-induced neuroplasticity |journal=Neuropsychopharmacology |volume=48 |issue=1 |pages=104–112 |date=January 2023 |pmid=36123427 |pmc=9700802 |doi=10.1038/s41386-022-01389-z |doi-access=free}}</ref><ref name="pmid35060714">{{cite journal |vauthors=Olson DE |title=Biochemical Mechanisms Underlying Psychedelic-Induced Neuroplasticity |journal=Biochemistry |volume=61 |issue=3 |pages=127–136 |date=February 2022 |pmid=35060714 |pmc=9004607 |doi=10.1021/acs.biochem.1c00812}}</ref>

The [[British people|British]] [[critical psychiatrist]] [[Joanna Moncrieff]] has critiqued the use and study of psychedelics like LSD for treatment of psychiatric disorders, highlighting concerns including excessive hype around these drugs, questionable biologically-based theories of benefit, blurred lines between medical and recreational use, flawed clinical trial findings, financial conflicts of interest, strong expectancy effects and large placebo responses, small and short-term benefits over placebo, and their potential for difficult experiences and adverse effects, among others.<ref name="Moncrieff2025">{{cite book | vauthors = Moncrieff J | chapter=Alternative Approaches: The Good, the Bad and the Worrying: Psychedelics for Depression | title=Chemically Imbalanced: The Making and Unmaking of the Serotonin Myth | publisher=Flint | date=16 January 2025 | isbn=978-1-80399-680-6 | url=https://books.google.com/books?id=e0MkEQAAQBAJ | access-date=16 October 2025 | page=}}</ref>

===Other conditions===
LSD has been studied for the relief of [[pain]] and [[headache]]s.<ref name="PassieHalpernStrichtenoth2008" /><ref>{{Cite web | vauthors = Jarow O |date=2024-05-15 |title=Psychedelics could treat some of the worst chronic pain in the world |url=https://www.vox.com/future-perfect/2024/5/15/24156372/psychedelics-chronic-pain-cluster-headache-medicine-lsd-psilocybin |access-date=2024-05-25 |website=Vox |language=en-US |archive-date=May 25, 2024 |archive-url=https://web.archive.org/web/20240525084603/https://www.vox.com/future-perfect/2024/5/15/24156372/psychedelics-chronic-pain-cluster-headache-medicine-lsd-psilocybin |url-status=live }}</ref><ref>{{Cite web |title=RFA-AG-25-004: Safety and Early Efficacy Studies of Psychedelic-Assisted Therapy for Chronic Pain in Older Adults (UG3/UH3 Clinical Trial Required) |url=https://grants.nih.gov/grants/guide/rfa-files/RFA-AG-25-004.html |access-date=2024-05-25 |website=grants.nih.gov |archive-date=May 25, 2024 |archive-url=https://web.archive.org/web/20240525084606/https://grants.nih.gov/grants/guide/rfa-files/RFA-AG-25-004.html |url-status=live }}</ref> It has been used as a treatment for [[cluster headache]]s with positive results in some small studies.<ref name="PassieHalpernStrichtenoth2008" /> The drug might have [[analgesic]] properties related to pain in [[terminal illness|terminally ill]] patients and [[phantom pain]] and might be useful for treating [[inflammatory disease]]s such as [[rheumatoid arthritis]] due to [[anti-inflammatory]] effects.<ref name=lsdpain>{{cite journal |vauthors=Whelan A, Johnson MI |title=Lysergic acid diethylamide and psilocybin for the management of patients with persistent pain: a potential role? |journal=Pain Management |volume=8 |issue=3 |pages=217–229 |date=May 2018 |pmid=29722608 |doi=10.2217/pmt-2017-0068 |s2cid=19160293 |url=http://eprints.leedsbeckett.ac.uk/4843/1/LysergicAcidDiethylamide%28LSD%29andPsilocybinAM-JOHNSON.pdf |access-date=August 22, 2020 |archive-date=October 8, 2020 |archive-url=https://web.archive.org/web/20201008201515/http://eprints.leedsbeckett.ac.uk/4843/1/LysergicAcidDiethylamide%28LSD%29andPsilocybinAM-JOHNSON.pdf |url-status=live}}</ref>

===Enhancing creativity===
In the 1950s and 1960s, some psychiatrists, such as [[Oscar Janiger]], explored the potential effect of LSD on [[creativity]]. Experimental studies attempted to measure the effect of LSD on creative activity and aesthetic appreciation.<ref name="PMID6054248"/><ref name="PMID18562421">{{cite journal |vauthors=Sessa B |title=Is it time to revisit the role of psychedelic drugs in enhancing human creativity? |journal=Journal of Psychopharmacology |volume=22 |issue=8 |pages=821–827 |date=November 2008 |pmid=18562421 |s2cid=1908638 |doi=10.1177/0269881108091597}}</ref><ref name="PMID2723891">{{cite journal |vauthors=Janiger O, Dobkin de Rios M |title=LSD and creativity |journal=Journal of Psychoactive Drugs |volume=21 |issue=1 |pages=129–134 |year=1989 |pmid=2723891 |doi=10.1080/02791072.1989.10472150 |url= http://www.erowid.org/culture/characters/janiger_oscar/janiger_oscar.shtml |archive-url=https://web.archive.org/web/20091003005533/http://www.erowid.org/culture/characters/janiger_oscar/janiger_oscar.shtml |archive-date=October 3, 2009 |url-status=live}}</ref><ref name="Stafford-Golightly">{{cite book |title=LSD, the problem-solving psychedelic |vauthors=Stafford PG, Golightly BH |year=1967 |url=http://www.psychedelic-library.org/staf3.htm |url-status=live |archive-url=https://web.archive.org/web/20120417105503/http://www.psychedelic-library.org//staf3.htm |archive-date =April 17, 2012}}</ref> In 1966, [[James Fadiman]] conducted a study with the central question "How can psychedelics be used to facilitate problem solving?" This study attempted to solve 44 different problems and had 40 satisfactory solutions when the FDA banned all research into psychedelics. LSD was a key component of this study.<ref>{{cite web |title=Scientific Problem Solving with Psychedelics – James Fadiman |website=[[YouTube]] |date=May 29, 2013 |url=https://www.youtube.com/watch?v=KtL5fafpRKc |access-date=2023-05-02 |language=en |archive-date=September 8, 2019 |archive-url=https://web.archive.org/web/20190908090741/https://www.youtube.com/watch?v=KtL5fafpRKc |url-status=live }}</ref><ref>{{cite book |vauthors=Fadiman J |title=The psychedelic explorer's guide: safe, therapeutic, and sacred journeys |date=2018 |publisher=Tantor Media |isbn=978-1-9773-7476-9 |oclc=1031461623}}</ref>

== See also ==
{{Portal|1960s}}

* [[Substituted lysergamide]]

== Notes ==
{{Notelist}}

== References ==
{{Reflist}}

== Further reading ==
* {{cite book | title = LSD: My Problem Child | author = [[Albert Hofmann]] | url = https://books.google.com/books?id=e5wQAQAAIAAJ | year = 1980| publisher = McGraw-Hill | isbn = 978-0-07-029325-0 }}

== External links ==
{{sister project links||d=Q23118|c=Category:Lysergic acid diethylamide|n=no|b=no|v=no|voy=no|m=no|mw=no|s=no|wikt=no|species=no}}
* [https://isomerdesign.com/pihkal/explore/5026 LSD - Isomer Design]
* [https://psychonautwiki.org/wiki/LSD LSD - PsychonautWiki]
* [https://www.erowid.org/chemicals/lsd/lsd.shtml LSD - Erowid]
* [https://www.erowid.org/library/books_online/tihkal/tihkal26.shtml LSD - TiHKAL - Erowid]
* [https://isomerdesign.com/pihkal/read/tk/26 LSD - TiHKAL - Isomer Design]
* [https://www.euda.europa.eu/publications/drug-profiles/lsd_en Lysergide (LSD) drug profile - EUDA (European Union Drugs Agency)]

===Documentaries===
* [http://www.nfb.ca/film/hofmanns_potion ''Hofmann's Potion''] {{Webarchive|url=https://web.archive.org/web/20210616120006/http://www.nfb.ca/film/hofmanns_potion/ |date=June 16, 2021 }} a documentary on the origins of LSD, 2002
* [https://web.archive.org/web/20091106130407/http://channel.nationalgeographic.com/series/explorer/4094/Overview ''Inside LSD''] National Geographic Channel, 2009
* ''[https://www.netflix.com/de-en/title/80229847 How to Change Your Mind] {{Webarchive|url=https://web.archive.org/web/20220616180919/https://www.netflix.com/de-en/title/80229847 |date=June 16, 2022 }}'' Netflix docuseries, 2022

{{Psychedelics}}
{{Drug use}}
{{Chemical agents}}
{{Navboxes
| title = [[Pharmacodynamics]]
| titlestyle = background:#ccccff
| list1 = 
{{Adrenergic receptor modulators}}
{{Dopamine receptor modulators}}
{{Serotonin receptor modulators}}
}}
{{Ergolines}}
{{Authority control}}

{{DEFAULTSORT:Lysergic Acid Diethylamide}}

[[Category:LSD| ]]
[[Category:1938 in science]]
[[Category:1938 in Switzerland]]
[[Category:1938 introductions]]
[[Category:5-HT1A agonists]]
[[Category:5-HT2A agonists]]
[[Category:5-HT2B agonists]]
[[Category:5-HT2C agonists]]
[[Category:Biased ligands]]
[[Category:Counterculture of the 1960s]]
[[Category:Diethylamino compounds]]
[[Category:Dopamine agonists]]
[[Category:Drugs developed by Novartis]]
[[Category:Enantiopure drugs]]
[[Category:Entheogens]]
[[Category:Experimental hallucinogens]]
[[Category:Incapacitating agents]]
[[Category:Light-sensitive chemicals]]
[[Category:Mind control]]
[[Category:Psychedelic-assisted therapy]]
[[Category:Psychedelic drug metabolites]]
[[Category:Psychedelic lysergamides]]
[[Category:Psychoplastogens]]
[[Category:Serotonin receptor agonists]]
[[Category:Swiss inventions]]
[[Category:TAAR1 modulators]]
[[Category:TiHKAL]]
[[Category:Wikipedia medicine articles ready to translate]]
[[Category:Articles containing video clips]]
[[Category:Experimental antidepressants]]