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Psilocybin

The primary psychoactive compound in psilocybin mushrooms, studied most heavily as an assisted therapy for depression, anxiety, and addiction.

State of the evidence

Synthesized

Synthesized from 25 studies in the library · AI-generated, grounded in the abstracts below

Found by searching the library for Psilocybin, magic mushrooms, psilocin, psychedelic mushrooms, then ranked by relevance.

Psilocybin, particularly at higher doses (20-30 mg) and combined with psychological support, shows rapid and sustained reductions in depression and anxiety in patients with life-threatening cancer and treatment-resistant depression, with effects lasting up to 6-12 months in open-label and controlled trials. A meta-analysis of six RCTs confirms standard-dose psilocybin is superior to control conditions for major depressive disorder, though a head-to-head trial found no significant difference versus escitalopram at 6 weeks. The evidence is promising but limited by small sample sizes, open-label designs, and lack of long-term durability data beyond 12 months.

Confidence in the evidence

Moderate
  • Multiple RCTs and a meta-analysis (6 RCTs) show consistent positive effects for depression and anxiety, but many studies are small (12-79 participants) and some are open-label.
  • The largest head-to-head trial (psilocybin vs. escitalopram) found no significant difference on the primary outcome, introducing some inconsistency.
  • Most trials include psychological support, making it difficult to isolate the drug effect from the therapeutic context, and blinding is often inadequate.
  • Long-term follow-up data are limited to 6-12 months, and durability beyond that is unknown.
How we rate confidence

Confidence reflects the strength of the underlying evidence, not whether the result is favorable. It weighs the number and size of studies, their design (randomized trials count for more than observational or single-case work), how consistently they point the same way, and their risk of bias.

Tiers run from Insufficient to High. High is rare in this field: small, early, or open-label studies land lower even when their direction is encouraging.

Evidence by study

Direction is each study's finding relative to your question: Supports, Opposes, No effect, Mixed, or Unclear.

High-dose psilocybin produced large decreases in depression and anxiety, sustained at 6 months with ~80% showing clinically significant improvement.

RCT Sample size: 51

Single-dose psilocybin produced immediate, substantial, and sustained improvements in anxiety and depression, with 60-80% maintaining reductions at 6.5 months.

RCT Sample size: 29

Psilocybin produced rapid and sustained antidepressant effects in treatment-resistant depression, with no control group.

open-label feasibility study Sample size: 12

No significant difference in antidepressant effects between psilocybin and escitalopram at week 6 on the primary outcome, though secondary outcomes favored psilocybin.

RCT

Two psilocybin sessions produced large antidepressant effects in MDD compared to a waiting-list control.

RCT Sample size: 27

Psilocybin significantly reduced anxiety at 1 and 3 months and improved depression at 6 months, with no serious adverse events.

RCT Sample size: 12

Psilocybin decreased cerebral blood flow and BOLD signal in hub regions like the thalamus and cingulate cortex, with decreased mPFC-PCC coupling predicting subjective effects.

observational (fMRI) Sample size: 30

Psilocybin significantly increased abstinence from alcohol after administration, with gains largely maintained up to 36 weeks.

proof-of-concept study Sample size: 10

Proposes the REBUS model: psychedelics relax the precision of high-level priors, enabling revision of maladaptive beliefs underlying mental illness.

theoretical

25 mg psilocybin significantly reduced depression at week 3 vs. 1 mg control, but sustained response at 12 weeks was not significant.

RCT Sample size: 233

Psilocybin induces a psychosis-like syndrome in humans, blocked by a serotonin-2A antagonist, suggesting a role for 5-HT2A overactivity in schizophrenia.

observational

Psilocybin produced large reductions in depressive symptoms at 5 weeks (Cohen's d=2.3) that remained significant at 6 months (d=1.4).

open-label trial Sample size: 20

Psilocybin at 20-30 mg/70 kg occasioned mystical-type experiences in 72% of volunteers, with sustained positive changes in attitudes, mood, and behavior at 14 months.

RCT Sample size: 18

80% of participants showed seven-day point prevalence abstinence at 6-month follow-up after psilocybin-assisted smoking cessation treatment.

open-label pilot study Sample size: 15

Psilocybin increased the personality trait of Openness, sustained over 1 year in those who had mystical experiences.

RCT

Psilocybin produced sustained improvements in anxiety (59% reduction at week 3) and quality of life through 12 months, though effects were not significant after accounting for depression improvement.

open-label trial Sample size: 15

Study investigates the role of the serotonin 5-HT2A receptor in psilocin's effect on social behavior deficits in mice.

preclinical (animal)

Therapeutic alliance had weaker direct effects on depression outcomes than the psychedelic experience itself, but alliance influenced the psychedelic experience.

post hoc analysis of RCT Sample size: 79

Reviews psilocybin's potential for tinnitus via 5-HT2A receptor activation, glutamate release, and BDNF upregulation, restoring neural plasticity.

review

Standard-dose psilocybin was superior to control in reducing depressive symptoms (SMD: -1.05) and associated with higher response and remission rates at 2-3 weeks.

meta-analysis

Identified reporting gaps in psilocybin trials: overrepresentation of prior psychedelic users, inconsistent reporting of therapy sessions, and lack of blinding success assessment.

descriptive review

Protocol for a study exploring psilocybin's acceptability and safety in bipolar II depression, a population typically excluded from trials.

protocol (open-label feasibility study)

Female participants reported more intense acute subjective effects and impairment under psilocybin than males, independent of drug concentration.

pooled analysis of two RCTs Sample size: 72

Psilocybin induced c-Fos expression in the nucleus accumbens, with 5-HT2A and 5-HT2B receptors mediating effects in neurons and non-neuronal cells.

preclinical (animal)

Study aims to characterize sex-specific effects of psilocybin on brain and behavior after developmental stress in a mouse model.

preclinical (animal)

Points of agreement

  • Psilocybin, especially at higher doses (20-30 mg), produces rapid and substantial reductions in depression and anxiety in cancer patients and those with treatment-resistant depression.
  • The therapeutic effects are often sustained for months (6-12 months) after a single or two doses.
  • The quality of the acute psychedelic experience (e.g., mystical-type experience) is consistently associated with better clinical outcomes.
  • Psilocybin is generally well-tolerated in controlled settings, with no serious adverse events reported in most trials.

Conflicts

  • One large RCT found no significant difference between psilocybin and escitalopram for depression at 6 weeks, while other trials show large effects versus placebo or waiting-list controls.
  • Sustained response at 12 weeks was not significant in one phase 2 trial, whereas other studies report maintained benefits up to 12 months.
  • Psilocybin can induce acute anxiety and psychosis-like symptoms in some individuals, contrasting with its therapeutic effects.

Gaps

  • Long-term durability beyond 12 months is unknown.
  • Most trials exclude patients with bipolar disorder, suicidality, or psychosis, limiting generalizability.
  • Blinding success, therapist fidelity, and expectancy effects are rarely reported, making it hard to isolate drug effects from psychological support.
  • Sex differences in response are understudied, with preliminary evidence suggesting females may experience more intense acute effects.
  • Optimal dosing, number of sessions, and the role of psychotherapy components remain unclear.
Browse these studies in the library
How we analyze this

This synthesis reads the 15 most-cited and 10 most recent studies whose primary subject is Psilocybin, up to 25 in all. The most-cited set anchors the established evidence, and the recent set surfaces work that is too new to have gathered citations yet.

A study qualifies only when Psilocybin or a known alias appears in its title or keywords, so broad reviews that mention it only in passing are left out. Each study is read from its abstract, strongest evidence first, and the summary reports the direction of the results along with any conflicts and gaps.

Latest monthly recap: June 2026 →

4,326 articles · 1,674 from the last two years · 14,543,251 participants across 1,298 studies reporting sample size

Common study designs

review 872 systematic review 216 experimental study 249 randomized controlled trial 157 theoretical or philosophical paper 253

New insights into the clinical and nonclinical effects of psychedelic substances: an integrative review

Matthias Forstmann, Christina Sagioglou preprint

After a long period of stagnation, research on psychedelic substances like LSD, psilocybin, and DMT has revived over the last decade, with major programs in Europe and the United States. This review summarizes recent insights into their potential for treating mental health disorders, effects on recreational users, and underlying neurological and cognitive processes. It covers the history of psychedelic research, objective and subjective effects, prevalence and correlates of use, and potential for harm. The review examines clinical benefits for major depression, anxiety, and substance use disorders, along with proposed neural and cognitive mechanisms. It also discusses effects on healthy subjects, including psychological wellbeing, personality changes, nature relatedness, and creativity, and concludes with long-term effects of single experiences.

Effectiveness and Experiences of Psychedelic-Based Interventions for the Treatment of Alcohol Use Disorder: A Mixed Methods Systematic Review

Baneet Gill

A mixed-methods systematic review of eight studies (four quantitative, four qualitative) examined the effectiveness and experiences of using psychedelics to treat alcohol use disorder (AUD). Quantitative studies reported an overall increase in abstinence and a decrease in drinking days after treatment, while qualitative studies reported mostly positive experiences. However, the included studies were rated mostly 'poor' or 'moderate' quality, so results should be interpreted with caution. The small number of recent studies, small sample sizes, and heterogeneity of studies limit the strength of conclusions, highlighting the need for further research.

Psychopathological descriptive model of hallucinogenic/psychedelic drugs effect in the treatment of depression and addictions

Nestor Girala

The efficacy of hallucinogenic drugs (ayahuasca, psilocybin, LSD, ketamine) in treating depression and addictions is accompanied by intense emotional states and mystical-type experiences, including feelings of oneness, transcendence, ineffability, and awe. These common psychopathological elements may mediate the drugs' therapeutic action. The paper reviews literature on subjective experiences during such treatments and compares them with other life-changing experiences, discussing the evolutionary value of these emotions for group cohesiveness and the recalibration of cognitions and emotions.

Binaries, Multitudes, and Beyond: A Client-Authored Case Study in Psychedelic-Assisted Therapy, Artificial Intelligence, and Narrative Agency

Mark A. Michaels

A client who is also the author documents a 10-week course of collaborative therapy that integrates EMDR, ketamine, MDMA, psilocybin, creative expression, and AI-assisted reflection and writing. Drawing on affect theory, mentalization, earned secure attachment, and Dabrowski's theory of positive disintegration, the paper analyzes how recognition of core affects, rupture-and-repair processes, and the reclamation of narrative agency contributed to rapid, positive change. Psychoeducation supported a deep exploration of these concepts. The case critiques traditional psychoanalytic framings, diagnostic overreach, and hierarchical therapeutic structures, arguing for a model emphasizing collaboration, agency, and narrative coherence. It also highlights the potential and limitations of generative AI as an adjunct in psychotherapy and narrative self-reclamation.

Malpractice without a Baseline: Tort Liability and the Structural Paradoxes of Psychedelic-assisted Therapy

Michael Palmieri

Psychedelic-assisted therapy is moving toward clinical legitimacy in the United States, with the FDA granting Breakthrough Therapy designations to psilocybin and MDMA and major research investments underway. However, the legal framework for malpractice liability in this field remains undeveloped. The article identifies three structural challenges: the standard of care is unclear because the profession lacks settled credentialing and practice standards; causation analysis is complicated when treatment intentionally alters a patient's evaluative framework; and damages calculations face a paradox when identity transformation may later be viewed as beneficial. The article argues these are permanent structural features, not transitional problems, and proposes doctrinal adaptations such as prospective consent architectures and tiered standard-of-care frameworks.

Consent Without Continuity: Psychedelic-Assisted Therapy and the Structural Failure of Informed Consent Doctrine

Michael Palmieri

American informed consent law assumes that a patient's values and decision-making framework remain stable from the moment they authorize a treatment through the period when they experience its effects. Psychedelic-assisted therapy, using compounds like psilocybin and MDMA, deliberately alters patients' values, self-concept, and evaluative frameworks as a therapeutic goal, breaking that continuity. This article argues that when a treatment transforms the cognitive architecture through which risk is assessed, standard consent doctrines—materiality, causation, and capacity—fail. The author proposes a dynamic consent model with pre-session identity-impact disclosures, staged reaffirmation checkpoints, integration-phase consent validation, and longitudinal documentation reforms.

Publication bias in randomized trials of psilocybin for depression: a Robust Bayesian Meta-Analysis

Çağrı Özkurt preprint

A re-analysis of 12 randomized controlled trials on psilocybin for depression found moderate evidence of publication bias, with a bias-corrected effect size about 41% smaller than originally reported. The original analysis reported a large effect (g = 0.90), but after accounting for selective reporting using Robust Bayesian Meta-Analysis, the effect dropped to about 0.53, with a credible interval that includes zero. This evidence of bias disappeared when open-label studies were excluded, suggesting expectancy-driven effects rather than suppressed negative results. The findings do not overturn the original conclusions but indicate greater uncertainty than previously thought.

Legalizing Magic Mushrooms: A Different Set of Laws for a Different Kind of Drug

Edward S. Adams

This article examines how the cannabis industry is regulated, tracing its origins, history, and flaws. It then compares the cannabis and psilocybin industries, arguing that the cannabis regulatory model should not be copied for psilocybin. Instead, the author proposes customized regulatory approaches that address psilocybin's distinct features, aiming to create a safe, effective, and well-regulated market.

The Birth of the Psychedelic Industry: Capitalizing on the Psychedelic Renaissance

Minsu Yoo, Sofia Sakopoulos

The commercialization of psychedelics like psilocybin, LSD, and MDMA for mental health treatment blurs the line between impartial science and profit-driven industry. Based on in-depth interviews with stakeholders, the study reveals how venture capitalists not only fund research but also provide regulatory and industry knowledge, creating ethical dilemmas for scientists. Researchers' reluctance to disclose personal psychedelic experiences during interviews signals a shift from an illegality paradigm to one of intellectual property. The findings suggest that ethical dynamics in scientific practice must be reconsidered, particularly how public and private funders shape researchers' priorities.

Psychedelics and autobiographical memory – Six open questions

Samuli Kangaslampi, Morten P. Lietz preprint

Psychedelics have long been thought to enhance autobiographical memory, and revisiting such memories may be key to their therapeutic effects, yet modern research has largely overlooked this area. This review identifies six open questions: whether psychedelics boost autobiographical recall; whether recalling significant or traumatic memories is common during psychedelic experiences; whether they can produce false memories; how memories change when recalled and reconsolidated under psychedelics; what memories of the psychedelic experience itself are like; and whether autobiographical experiences under psychedelics are especially important for therapeutic outcomes. The authors present the limited current evidence for each question and propose how future studies could address them, emphasizing relevance for optimizing psychedelic-assisted therapies and avoiding harm.

Clinical trials

All Psilocybin trials →