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Psilocybin

Drugs and Chemicals · NLM MeSH · updated 2026-10-31 · version 1

Citations verified against PubMedNot yet clinician-reviewed10 referencesApproximately 5 min read

The major of two hallucinogenic components of the sacred Teonanacatl mushrooms (see psilocybe), the other component being psilocin.

Table of Contents

1. Definition2. Research landscape3. Reading the evidence4. Open-access studies5. Key reviews6. References7. About this article

Definition and research guide

This page combines a MeSH definition, publication statistics and selected research abstracts. It is a starting point for reading the literature, not a medical textbook or a systematic evidence review.

Content available: 4 complete abstracts (1,021 words), 10 references. Full article text is not stored or reproduced here; follow the PMID, DOI or PMC links to read the original sources and their access terms.

Definition

The major of two hallucinogenic components of the sacred Teonanacatl mushrooms (see psilocybe), the other component being psilocin.

Definition: NLM Medical Subject Headings (MeSH) scope note (Public domain (U.S. National Library of Medicine); attribution requested). View the MeSH record.

Also known as: 1H-Indol-4-ol, 3-(2-(Dimethylamino)ethyl)-, Dihydrogen Phosphate (ester); Psilocybine; Psilocibin.

Where it fits in the MeSH classification

Broader topics
Indole Alkaloids; Tryptamines

Related concepts

  • Psilocybe
  • Psilocin

Research landscape

PubMed indexes 1,860 records tagged with the MeSH heading “Psilocybin” (counts retrieved 2026-10-31). 1,141 of them (61.3%) were published from 2020 onward, and the busiest period so far is 2020 onward with 1,141 records.

Reviews account for 439 records (23.6%) and meta-analyses for 45. Randomized controlled trials number 124 (6.7%) as a share of all records on the topic.

PubMed records by publication periodthrough 1999: 427 records; 2000-2009: 81 records; 2010-2019: 211 records; 2020 onward: 1,141 records427through 1999812000-20092112010-20191,1412020 onward
Records in PubMed indexed with this heading, by publication period. Real counts from NCBI E-utilities; the final period covers only part of the current year. Volume reflects how much has been published, not how strong the evidence is.
Show the data
PeriodRecords
through 1999427
2000-200981
2010-2019211
2020 onward1,141
Share of records by publication typeReviews: 23.6 percent; Meta-analyses: 2.4 percent; Randomized controlled trials: 6.7 percentReviews23.6% (439)Meta-analyses2.4% (45)Randomized controlled trials6.7% (124)
Share of all PubMed records on this heading that carry each publication type. Types overlap with other records, so the shares do not sum to 100%.
Publication-type chart data
Publication types among 1,860 PubMed records
TypeRecordsShare
Reviews43923.6%
Meta-analyses452.4%
Randomized controlled trials1246.7%

Method: PubMed query "Psilocybin"[MeSH Terms] with publication-type and date filters, retrieved 2026-10-31.

Reading the evidence in drugs and chemicals

Studies of a chemical or drug can answer very different questions: what it is and how it behaves in cells and animals, how the body handles it, and whether it changes outcomes in people. Laboratory and animal findings often do not carry over to patients, and observational studies of exposures are confounded by who uses a substance and why. Nothing on this page is a recommendation to use, avoid, start or stop any substance or medicine; talk to a qualified clinician or pharmacist about your own situation. Check the dose, the species, the comparison group and whether a patient-relevant outcome was measured.

Evidence from open-access studies

These open-access studies come from PubMed’s best-match results for this heading (papers whose main topic it is), ranked here by citation count, with one recent addition. Each abstract is reproduced in full under its recorded open licence so that you can read the authors’ own words. They illustrate the literature; they are not a systematic summary of it. Citation counts measure attention, not reliability or clinical benefit.

Study comparison — selected abstracts, not a systematic review
Study / authorsYearSource label / designEurope PMC citationsLicence / source
Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial
Griffiths RR, Johnson MW, Carducci MA, Umbricht A, Richards WA, Richards BD, et al.
2016Randomized controlled trial
Design not recorded in structured metadata
1,505cc by
PMID 27909165 · DOI · PMC5367557
Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial
Ross S, Bossis A, Guss J, Agin-Liebes G, Malone T, Cohen B, et al.
2016Randomized controlled trial
Design not recorded in structured metadata
1,162cc by
PMID 27909164 · DOI · PMC5367551
Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial
Davis AK, Barrett FS, May DG, Cosimano MP, Sepeda ND, Johnson MW, et al.
2021Randomized controlled trial
Design not recorded in structured metadata
945cc by
PMID 33146667 · DOI · PMC7643046
Human brain changes after first psilocybin use
Lyons T, Spriggs M, Kerkelä L, Rosas FE, Roseman L, Mediano PAM, et al.
2026Research article
Design not recorded in structured metadata
21cc by
PMID 42086570 · DOI · PMC13144397

Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial [1]

Randomized controlled trial Griffiths RR, Johnson MW, Carducci MA, Umbricht A, Richards WA, Richards BD, et al. · · 2016 · cited 1,505 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
Cancer patients often develop chronic, clinically significant symptoms of depression and anxiety.
Closing excerpt
gov identifier: NCT00465595.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (211 words)

Cancer patients often develop chronic, clinically significant symptoms of depression and anxiety. Previous studies suggest that psilocybin may decrease depression and anxiety in cancer patients. The effects of psilocybin were studied in 51 cancer patients with life-threatening diagnoses and symptoms of depression and/or anxiety. This randomized, double-blind, cross-over trial investigated the effects of a very low (placebo-like) dose (1 or 3 mg/70 kg) vs. a high dose (22 or 30 mg/70 kg) of psilocybin administered in counterbalanced sequence with 5 weeks between sessions and a 6-month follow-up. Instructions to participants and staff minimized expectancy effects. Participants, staff, and community observers rated participant moods, attitudes, and behaviors throughout the study. High-dose psilocybin produced large decreases in clinician- and self-rated measures of depressed mood and anxiety, along with increases in quality of life, life meaning, and optimism, and decreases in death anxiety. At 6-month follow-up, these changes were sustained, with about 80% of participants continuing to show clinically significant decreases in depressed mood and anxiety. Participants attributed improvements in attitudes about life/self, mood, relationships, and spirituality to the high-dose experience, with >80% endorsing moderately or greater increased well-being/life satisfaction. Community observer ratings showed corresponding changes. Mystical-type psilocybin experience on session day mediated the effect of psilocybin dose on therapeutic outcomes.Trial registrationClinicalTrials.gov identifier: NCT00465595.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 27909165 · DOI · PMC5367557

Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial [2]

Randomized controlled trial Ross S, Bossis A, Guss J, Agin-Liebes G, Malone T, Cohen B, et al. · · 2016 · cited 1,162 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
BackgroundClinically significant anxiety and depression are common in patients with cancer, and are associated with poor psychiatric and medical outcomes.
Closing excerpt
gov Identifier: NCT00957359.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (193 words)

BackgroundClinically significant anxiety and depression are common in patients with cancer, and are associated with poor psychiatric and medical outcomes. Historical and recent research suggests a role for psilocybin to treat cancer-related anxiety and depression.MethodsIn this double-blind, placebo-controlled, crossover trial, 29 patients with cancer-related anxiety and depression were randomly assigned and received treatment with single-dose psilocybin (0.3 mg/kg) or niacin, both in conjunction with psychotherapy. The primary outcomes were anxiety and depression assessed between groups prior to the crossover at 7 weeks.ResultsPrior to the crossover, psilocybin produced immediate, substantial, and sustained improvements in anxiety and depression and led to decreases in cancer-related demoralization and hopelessness, improved spiritual wellbeing, and increased quality of life. At the 6.5-month follow-up, psilocybin was associated with enduring anxiolytic and anti-depressant effects (approximately 60-80% of participants continued with clinically significant reductions in depression or anxiety), sustained benefits in existential distress and quality of life, as well as improved attitudes towards death. The psilocybin-induced mystical experience mediated the therapeutic effect of psilocybin on anxiety and depression.ConclusionsIn conjunction with psychotherapy, single moderate-dose psilocybin produced rapid, robust and enduring anxiolytic and anti-depressant effects in patients with cancer-related psychological distress.Trial registrationClinicalTrials.gov Identifier: NCT00957359.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 27909164 · DOI · PMC5367551

Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial [3]

Randomized controlled trial Davis AK, Barrett FS, May DG, Cosimano MP, Sepeda ND, Johnson MW, et al. · · 2021 · cited 945 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
ImportanceMajor depressive disorder (MDD) is a substantial public health burden, but current treatments have limited effectiveness and adherence.
Closing excerpt
gov Identifier: NCT03181529.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (440 words)

ImportanceMajor depressive disorder (MDD) is a substantial public health burden, but current treatments have limited effectiveness and adherence. Recent evidence suggests that 1 or 2 administrations of psilocybin with psychological support produces antidepressant effects in patients with cancer and in those with treatment-resistant depression.ObjectiveTo investigate the effect of psilocybin therapy in patients with MDD.Design, setting, and participantsThis randomized, waiting list-controlled clinical trial was conducted at the Center for Psychedelic and Consciousness Research at Johns Hopkins Bayview Medical Center in Baltimore, Maryland. Adults aged 21 to 75 years with an MDD diagnosis, not currently using antidepressant medications, and without histories of psychotic disorder, serious suicide attempt, or hospitalization were eligible to participate. Enrollment occurred between August 2017 and April 2019, and the 4-week primary outcome assessments were completed in July 2019. A total of 27 participants were randomized to an immediate treatment condition group (n = 15) or delayed treatment condition group (waiting list control condition; n = 12). Data analysis was conducted from July 1, 2019, to July 31, 2020, and included participants who completed the intervention (evaluable population).InterventionsTwo psilocybin sessions (session 1: 20 mg/70 kg; session 2: 30 mg/70 kg) were given (administered in opaque gelatin capsules with approximately 100 mL of water) in the context of supportive psychotherapy (approximately 11 hours). Participants were randomized to begin treatment immediately or after an 8-week delay.Main outcomes and measuresThe primary outcome, depression severity was assessed with the GRID-Hamilton Depression Rating Scale (GRID-HAMD) scores at baseline (score of ≥17 required for enrollment) and weeks 5 and 8 after enrollment for the delayed treatment group, which corresponded to weeks 1 and 4 after the intervention for the immediate treatment group. Secondary outcomes included the Quick Inventory of Depressive Symptomatology-Self Rated (QIDS-SR).ResultsOf the randomized participants, 24 of 27 (89%) completed the intervention and the week 1 and week 4 postsession assessments. This population had a mean (SD) age of 39.8 (12.2) years, was composed of 16 women (67%), and had a mean (SD) baseline GRID-HAMD score of 22.8 (3.9). The mean (SD) GRID-HAMD scores at weeks 1 and 4 (8.0 [7.1] and 8.5 [5.7]) in the immediate treatment group were statistically significantly lower than the scores at the comparable time points of weeks 5 and 8 (23.8 [5.4] and 23.5 [6.0]) in the delayed treatment group. The effect sizes were large at week 5 (Cohen d = 2.5; 95% CI, 1.4-3.5; P Conclusions and relevanceFindings suggest that psilocybin with therapy is efficacious in treating MDD, thus extending the results of previous studies of this intervention in patients with cancer and depression and of a nonrandomized study in patients with treatment-resistant depression.Trial registrationClinicalTrials.gov Identifier: NCT03181529.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 33146667 · DOI · PMC7643046

Human brain changes after first psilocybin use [4]

Research article Lyons T, Spriggs M, Kerkelä L, Rosas FE, Roseman L, Mediano PAM, et al. · · 2026 · cited 21 times (Europe PMC)

Abstract reading summary — source excerpts
Opening excerpt
Psychedelics have robust effects on acute brain function and long-term behavior but whether they also cause enduring functional and anatomical brain changes is largely unknown.
Closing excerpt
All effects are exclusive to 25 mg psilocybin; no effects occur with a 1 mg psilocybin placebo.
Interpretation limits
Verbatim excerpts from the authors’ abstract; the closing excerpt may describe a finding, limitation or recommendation. Design, population, effect size and uncertainty have not been independently extracted or appraised. Read the complete abstract and linked paper before interpreting the findings.
Read complete abstract (177 words)

Psychedelics have robust effects on acute brain function and long-term behavior but whether they also cause enduring functional and anatomical brain changes is largely unknown. In an exploratory, placebo-controlled, within-subjects, electroencephalography (EEG), and magnetic resonance imaging (MRI) study in 28 healthy, entirely psychedelic-naive participants, anatomical and functional brain changes are detected from one-hour to one-month after a single high-dose (25 mg) of psilocybin. Increases in cognitive flexibility, psychological insight, and well-being are seen at one-month. Diffusion tensor imaging (DTI) done before and one-month after 25 mg psilocybin reveals decreased axial diffusivity bilaterally in prefrontal-subcortical tracts that correlate with decreases in brain network modularity (fMRI) over the same month. Enduring functional brain changes are largely absent, but network modularity change (numerical decrease) negatively correlates with well-being change (significant increase), in line with previous findings in depression. Increased cortical signal entropy (EEG) at 1- and 2-hours post-dosing predicts improved psychological well-being at one-month. Next-day psychological insight mediates the entropy to well-being relationship. All effects are exclusive to 25 mg psilocybin; no effects occur with a 1 mg psilocybin placebo.

Abstract reproduced from the open-access article under the recorded cc by licence; © the authors. PMID 42086570 · DOI · PMC13144397

Key reviews and meta-analyses

The most cited review-type papers among PubMed’s best-match results for this heading, listed with bibliographic details only. Follow the links for the full text and access terms.

  • Research article The Therapeutic Potential of Psychedelic Drugs: Past, Present, and Future [5]
    Carhart-Harris RL, Goodwin GM · Neuropsychopharmacology · 2017 · cited 444 times (Europe PMC)
  • Research article Validation of the revised Mystical Experience Questionnaire in experimental sessions with psilocybin [6]
    Barrett FS, Johnson MW, Griffiths RR · J Psychopharmacol · 2015 · cited 444 times (Europe PMC)
  • Research article The pharmacology of psilocybin [7]
    Passie T, Seifert J, Schneider U, Emrich HM · Addict Biol · 2002 · cited 286 times (Europe PMC)
  • Research article The abuse potential of medical psilocybin according to the 8 factors of the Controlled Substances Act [8]
    Johnson MW, Griffiths RR, Hendricks PS, Henningfield JE · Neuropharmacology · 2018 · cited 246 times (Europe PMC)
  • Research article Potential Therapeutic Effects of Psilocybin [9]
    Johnson MW, Griffiths RR · Neurotherapeutics · 2017 · cited 204 times (Europe PMC)
  • Research article Psilocybin--summary of knowledge and new perspectives [10]
    Tylš F, Páleníček T, Horáček J · Eur Neuropsychopharmacol · 2014 · cited 179 times (Europe PMC)

References

  1. Griffiths RR, Johnson MW, Carducci MA, Umbricht A, Richards WA, Richards BD, et al.. Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial. . 2016. PMID 27909165 · DOI · PMC5367557
  2. Ross S, Bossis A, Guss J, Agin-Liebes G, Malone T, Cohen B, et al.. Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial. . 2016. PMID 27909164 · DOI · PMC5367551
  3. Davis AK, Barrett FS, May DG, Cosimano MP, Sepeda ND, Johnson MW, et al.. Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial. . 2021. PMID 33146667 · DOI · PMC7643046
  4. Lyons T, Spriggs M, Kerkelä L, Rosas FE, Roseman L, Mediano PAM, et al.. Human brain changes after first psilocybin use. . 2026. PMID 42086570 · DOI · PMC13144397
  5. Carhart-Harris RL, Goodwin GM. The Therapeutic Potential of Psychedelic Drugs: Past, Present, and Future. Neuropsychopharmacology. 2017. PMID 28443617 · DOI · PMC5603818
  6. Barrett FS, Johnson MW, Griffiths RR. Validation of the revised Mystical Experience Questionnaire in experimental sessions with psilocybin. J Psychopharmacol. 2015. PMID 26442957 · DOI · PMC5203697
  7. Passie T, Seifert J, Schneider U, Emrich HM. The pharmacology of psilocybin. Addict Biol. 2002. PMID 14578010 · DOI
  8. Johnson MW, Griffiths RR, Hendricks PS, Henningfield JE. The abuse potential of medical psilocybin according to the 8 factors of the Controlled Substances Act. Neuropharmacology. 2018. PMID 29753748 · DOI · PMC6791528
  9. Johnson MW, Griffiths RR. Potential Therapeutic Effects of Psilocybin. Neurotherapeutics. 2017. PMID 28585222 · DOI · PMC5509636
  10. Tylš F, Páleníček T, Horáček J. Psilocybin--summary of knowledge and new perspectives. Eur Neuropsychopharmacol. 2014. PMID 24444771 · DOI

About this article

Sources
NLM Medical Subject Headings (definition, synonyms); NCBI PubMed (counts, identifiers); Europe PMC (open-access abstracts and citation counts).
Verification
Every reference was resolved against PubMed on 2026-10-31; title, year and DOI matched.
Review state
automated source verified; no human expert review has been recorded yet.
Version
1, last updated 2026-10-31.

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At a glance

1,860
PubMed records on this heading
61%
published since 2020
439
review articles
124
randomized trials
10
verified references below

Counts come from PubMed on 2026-10-31; they show how much has been written, not how strong the evidence is.

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