Eighteen participants sampled from a large randomised, open-label phase 2 trial of psilocybin-assisted therapy for generalised anxiety disorder gave 29 semi-structured interviews before and after their dosing sessions, and the transcripts were analysed thematically. The subject was co-therapy, the common arrangement in which two therapists support one participant through dosing and psychotherapy. The authors report three themes: what the pair meant for safety, trust and the practical realities of access on dosing day; how the pair shaped the therapy itself; and how it shaped the weight and credibility participants gave to insights from the session. They present co-therapy as a safety measure that can also carry the therapy further, while raising questions of feasibility and accessibility.
Psilocybin research, 1958 to 2026
164 peer-reviewed studies, each summarized in plain English and linked to the paper itself. They are grouped by the condition studied, from depression to cluster headache, and you can filter by condition, study design, or decade.
Trials started each year
These bars count registered clinical trials, not the studies below. Every trial the register holds, by the year it began, so the shape is the field’s and not a picture of what we have read.
A further 6 trials are registered to start after 2026, and are not drawn.
Which trials are recruiting now →
9 trials began between 2004 and 2013; 74 started in 2026, the busiest year on the register.
Added in the latest review
68 studies were added on 21 Sep 2026. Three are below; the rest are in the register.
The 2023 International Cannabis Policy Study asked respondents in Canada, the United States, Australia and New Zealand about lifetime, past-year and past-month use of psilocybin, LSD, MDMA and ketamine, whether they had discussed such use with a medical professional...
Nine adults aged between eighteen and sixty-five who met criteria for both major depressive disorder and borderline personality disorder received a single dose of psilocybin in an open-label pilot.
Six studies to start with
Each with a line on why it matters. New to the evidence, start here; everything else is below.
Adverse Events in Studies of Classic Psychedelics: A Systematic Review and Meta-Analysis
JAMA Psychiatry meta-analysis of 114 studies and 3,504 people summarizing reported harms; the safety anchor a skeptic asks for.
Single-Dose Psilocybin Treatment for Major Depressive Disorder: A Randomized Clinical Trial
JAMA multi-site randomized trial in 104 adults with major depression; extends the evidence beyond treatment-resistant cases.
Single-Dose Psilocybin for a Treatment-Resistant Episode of Major Depression
NEJM phase 2b in 233 patients across 10 countries; the largest controlled psilocybin depression trial and the basis for phase 3.
Trial of Psilocybin versus Escitalopram for Depression
First head-to-head test against a standard antidepressant; NEJM, 59 patients, no significant difference on the main measure.
Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial
Johns Hopkins randomized double-blind trial in 51 people with cancer distress; a cornerstone of the modern psilocybin research era.
Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial
NYU randomized trial in 29 cancer patients, published the same day as the Johns Hopkins study; together they anchored the field.
All 164 studies
Filter 164 studies
Depression and mood
Efficacy and Safety of Psilocybin in Treatment-Resistant Major Depression: The EPISODE Randomized Clinical Trial
This phase 2b, triple-blind randomized clinical trial at two German university hospitals tested psilocybin for treatment-resistant major depression in 144 participants.
Psilocybin-assisted therapy for treatment-resistant major depressive disorder in a public healthcare setting: a randomized controlled trial
A two-arm, double-blind, placebo-controlled feasibility trial run at a single National Health Service site in England.
Real-World Psilocybin Therapy for Treatment-Resistant Depression: A Retrospective Observational Study
A retrospective review of medical records for 19 patients with treatment-resistant depression treated with psilocybin at 20 to 35 mg across one to four dosing sessions at the Psychiatric University Hospital Zurich, under the Swiss framework that permits limited medical use.
Long-Term Efficacy of Psilocybin with Adjunct Psychotherapy in Treatment-Resistant Major Depression: 6- and 12-Month Naturalistic Follow-Up of a Phase 2b Trial
This paper follows participants from a randomised, active placebo-controlled phase 2b trial of psilocybin with psychotherapy for treatment-resistant depression out to six and twelve months.
The role of the psychedelic experience in psilocybin treatment for treatment-resistant depression
Two hundred and thirty-three people with treatment-resistant depression received a single dose of COMP360, a pharmaceutical-grade synthesised psilocybin formulation developed by the trial's sponsor, at one of three strengths with psychological support.
Single-Dose Synthetic Psilocybin With Psychotherapy for Treatment-Resistant Bipolar Type II Major Depressive Episodes: A Nonrandomized Open-Label Trial
A 2024 nonrandomized, open-label trial (n=15) conducted at Sheppard Pratt gave adults with treatment-resistant bipolar II disorder, during a major depressive episode, a single 25 mg dose of synthetic psilocybin alongside psychotherapy...
Single-Dose Psilocybin Treatment for Major Depressive Disorder: A Randomized Clinical Trial
This phase 2, double-blind randomized clinical trial enrolled 104 adults with moderate-to-severe major depressive disorder across 11 U.S. sites.
Single-dose psilocybin-assisted therapy in major depressive disorder: a placebo-controlled, double-blind, randomised clinical trial
This randomized, double-blind, placebo-controlled trial (n=52), published in eClinicalMedicine, gave adults with major depressive disorder either a single moderate weight-adjusted dose of psilocybin or a placebo, each alongside psychological support.
Single-Dose Psilocybin for a Treatment-Resistant Episode of Major Depression
This 2022 phase 2b, double-blind, randomized trial (n=233) tested a single dose of a synthetic psilocybin formulation (COMP360) given with psychological support to adults with treatment-resistant depression, across 22 sites in 10 countries.
Efficacy and safety of psilocybin-assisted treatment for major depressive disorder: Prospective 12-month follow-up
This 2022 paper reported a prospective 12-month follow-up (n=24) of a Johns Hopkins trial in which adults with major depression received two doses of psilocybin alongside supportive psychotherapy.
Effects of Psilocybin-Assisted Therapy on Major Depressive Disorder: A Randomized Clinical Trial
In this randomized, waiting-list-controlled trial at Johns Hopkins, 27 adults with major depressive disorder were assigned to receive psilocybin-assisted therapy either immediately or after an eight-week delay; 24 completed the intervention...
Trial of Psilocybin versus Escitalopram for Depression
A 2021 phase 2, double-blind, randomized controlled trial (n=59) compared two sessions of psilocybin with a six-week course of the antidepressant escitalopram in adults with long-standing moderate-to-severe depression.
Psilocybin with psychological support for treatment-resistant depression: six-month follow-up
This 2018 open-label study followed up the same 20 patients with severe, treatment-resistant unipolar depression who had received two oral doses of psilocybin (10 mg then 25 mg, seven days apart) with psychological support.
Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study
In this open-label feasibility study, researchers at Imperial College London gave 20 patients with treatment-resistant depression two oral doses of psilocybin (10 mg, then 25 mg a week later) alongside psychological support.
Changes in anxiety, quality of life, and functioning following psilocybin-assisted therapy in veterans with treatment-resistant depression
Exploratory findings from an open-label trial in 15 US veterans with treatment-resistant depression who received a single 25 mg dose of psilocybin with psychological support, followed to 12 months with 10 completing long-term follow-up.
An Open-Label Study of Single-Dose Psilocybin for Borderline Personality Disorder With Co-Occurring Major Depressive Disorder
Nine adults aged between eighteen and sixty-five who met criteria for both major depressive disorder and borderline personality disorder received a single dose of psilocybin in an open-label pilot.
Cognitive outcomes following psilocybin-assisted therapy in treatment-resistant depression: A post-hoc analysis of a randomized, waitlist-controlled trial
This retrospective analysis covered 26 adults with treatment-resistant unipolar or bipolar depression who had taken part in an open-label trial of psilocybin-assisted psychotherapy.
Psilocybin with psychotherapeutic support for treatment-resistant depression: a pilot clinical trial
An open-label, single-arm pilot gave adults with treatment-resistant depression two psilocybin sessions alongside three preparatory and six integration sessions.
Psilocybin for treatment resistant depression in patients taking a concomitant SSRI medication
This phase 2, open-label exploratory study examined whether an ongoing SSRI blunts the response to a single 25 mg dose of synthetic psilocybin (COMP360) given with psychological support.
Cancer and end-of-life distress
Safety and Efficacy of Psilocybin During Anticancer Treatment: A Phase II Trial Secondary Analysis
A secondary analysis of a phase 2 open-label single-arm trial in 30 adults with cancer and major depressive disorder, comparing those receiving systemic anticancer treatment within 30 days of dosing (17 participants) against those not (13). All received preparation therapy...
Psilocybin-assisted psychotherapy for depression and anxiety associated with life threatening illness: A phase 2b randomized controlled trial
A 2025 double-blind, randomized phase 2b trial in Australia (n=35; 17 received psilocybin, 18 received placebo) tested a single 25 mg dose of psilocybin against 100 mg niacin as an active placebo, each paired with psychotherapy...
Long-term benefits of single-dose psilocybin in depressed patients with cancer
A phase 2 trial gave a single dose of psilocybin with psychological support to thirty people who had cancer and major depressive disorder, delivered in a community cancer setting.
Long-term follow-up of psilocybin-assisted psychotherapy for psychiatric and existential distress in patients with life-threatening cancer
This 2020 study reports long-term follow-up of the NYU trial cohort, surveying surviving participants who had received a single psilocybin session for cancer-related psychiatric and existential distress at roughly 3.2 and 4.5 years afterward.
Psilocybin produces substantial and sustained decreases in depression and anxiety in patients with life-threatening cancer: A randomized double-blind trial
In this randomized, double-blind crossover trial at Johns Hopkins, 51 people with life-threatening cancer and symptoms of depression and/or anxiety received a very low, placebo-like dose of psilocybin and a high dose in counterbalanced order, five weeks apart.
Rapid and sustained symptom reduction following psilocybin treatment for anxiety and depression in patients with life-threatening cancer: a randomized controlled trial
In this double-blind, placebo-controlled crossover trial at New York University, 29 patients with cancer-related anxiety and depression were randomly assigned to a single dose of psilocybin (0.3 mg/kg) or niacin as a control, each paired with psychotherapy.
Pilot study of psilocybin treatment for anxiety in patients with advanced-stage cancer
A 2011 double-blind, placebo-controlled pilot study (n=12) gave adults with advanced-stage cancer and anxiety a moderate dose of psilocybin (0.2 mg/kg) and a placebo (niacin) in separate sessions.
Developing Methods for Observing Awe Narration in Psilocybin-Assisted Therapy
This brief report describes building a way to observe and code the moments when a participant narrates an experience of awe during psilocybin-assisted therapy.
Learnings from a hybrid communities of practice group therapy model to support psilocybin-assisted therapy for patients with a terminal diagnosis
Twenty-five people in distress related to a terminal health condition took part in six to eight weekly online group sessions built around a resilience curriculum, combined with one in-person psilocybin-assisted therapy session...
Meaning-Centered Psychotherapy for Psilocybin-Assisted Therapy Among Patients with Advanced Cancer and Depression: Rationale and Preliminary Evaluation of MCP-PSIL
Meaning-centered psychotherapy is a short manual-based therapy built to strengthen a person's sense of meaning and purpose.
Participants' Music Experiences Associated With Psychedelic-Assisted Psychotherapy for Life-Threatening Illness: Interpretivist Research
This qualitative study examined what participants said about music during psilocybin-assisted psychotherapy for depression and anxiety tied to life-threatening illness.
Sense-Making Around Psilocybin in UK Women Experiencing Cancer-Related Existential Distress: An Interpretative Phenomenological Analysis
Seven women in the United Kingdom with a current or previous cancer diagnosis were interviewed about psilocybin, four of whom had used it and three of whom had considered it.
Stepping back into life: How Psychedelic Assisted Psychotherapy transforms the way of life of the terminally ill
This interpretative phenomenological study asked how psychedelic-assisted psychotherapy changes the way terminally ill people live.
The need for another tool: Australian healthcare professionals on the use of psilocybin for existential distress in people with cancer
Qualitative semi-structured interviews with 11 Australian healthcare professionals across specialties, largely from cancer centres including Chris O'Brien Lifehouse and Peter MacCallum, analysed by reflexive thematic analysis.
A critical evaluation of psilocybin-assisted therapy protocol components from clinical trial patients, facilitators, and caregivers
The authors used the Enhanced Critical Incident Technique to interview people involved in an open-label trial of psilocybin-assisted therapy for cancer-related demoralization and chronic pain.
Set and setting in psilocybin-assisted therapy: A qualitative study of patients with cancer and depression
Twenty-eight people taking part in a clinical trial of psilocybin-assisted therapy for cancer-related depression gave semi-structured interviews about the treatment and the setting around it, analysed with a template method.
Acute and Sustained Reductions in Loss of Meaning and Suicidal Ideation Following Psilocybin-Assisted Psychotherapy for Psychiatric and Existential Distress in Life-Threatening Cancer
This 2021 paper is a secondary analysis of the NYU randomized cancer trial (n=29) focused on existential outcomes.
Psilocybin-assisted group therapy for demoralized older long-term AIDS survivor men: An open-label safety and feasibility pilot study
This 2020 open-label pilot study tested the safety and feasibility of psilocybin-assisted group therapy in 18 older gay-identified men who had survived an HIV/AIDS diagnosis from before 1996 and had clinically significant demoralization.
Addiction and substance use
Psilocybin-assisted therapy for relapse prevention in alcohol use disorder: a phase 2 randomized clinical trial
A 2025 single-center, double-blind, randomized phase 2 trial in Switzerland (37 completers; 18 psilocybin, 19 placebo) tested a single 25 mg dose of psilocybin against placebo (mannitol), each combined with brief psychotherapy...
Psilocybin in alcohol use disorder and comorbid depressive symptoms: Results from a feasibility randomized clinical trial
A 2025 single-center, double-blind, randomized pilot trial (n=30 adults with severe alcohol use disorder and depression, allocated 2:1) compared a single 25 mg psilocybin session plus psychotherapy (n=20) against a 1 mg comparison dose (n=10), added to inpatient relapse-prevention care.
Percentage of Heavy Drinking Days Following Psilocybin-Assisted Psychotherapy vs Placebo in the Treatment of Adult Patients With Alcohol Use Disorder: A Randomized Clinical Trial
A 2022 double-blind randomized clinical trial (95 adults randomized, 93 treated) compared two psilocybin-assisted psychotherapy sessions (25-40 mg per 70 kg) against an active placebo (diphenhydramine), each combined with 12 psychotherapy sessions, in people with alcohol use disorder.
Long-term follow-up of psilocybin-facilitated smoking cessation
A 2017 long-term follow-up of the 15-participant open-label smoking-cessation pilot reported that 10 participants (67%) were confirmed abstinent at 12 months, and 9 (60%) remained abstinent at a later follow-up averaging about 30 months.
Pilot study of the 5-HT2AR agonist psilocybin in the treatment of tobacco addiction
A 2014 open-label pilot study (n=15 nicotine-dependent smokers) tested psilocybin delivered within a structured cognitive behavioral therapy program for smoking cessation.
Craving Reduction and Smoking Outcomes in Psilocybin-Assisted and Standard Cessation Care
An observational cohort compared smoking outcomes under psilocybin-assisted care and standard cessation care, sorting participants into a group whose smoking was driven mainly by dependence and a group whose smoking sat alongside affective symptoms.
Insights from the psychedelic experience integration session: Verbatims differentiate 3-month abstinence in alcohol use disorder with depressive symptoms
Twenty recently detoxified patients with alcohol use disorder and persisting depressive symptoms, all of them in the active psilocybin arm of a randomised trial, sat for a semi-structured integration interview the day after dosing.
Associations between psychedelic use and cannabis use disorder in a nationally representative sample
Using National Survey on Drug Use and Health data from 2015 to 2019 and 2021 to 2022, the authors ran survey-weighted logistic regressions testing whether use of particular psychedelics was associated with cannabis use disorder in the past year.
Multidimensional Personality Changes Following Psilocybin-Assisted Therapy in Patients With Alcohol Use Disorder: Results From a Double-Blind, Placebo-Controlled Clinical Trial
Eighty-four adults with alcohol use disorder were randomised to two medication sessions of either psilocybin or diphenhydramine as an active placebo, alongside twelve weekly psychotherapy sessions and a further twenty-four weeks of follow-up.
Psilocybin-assisted psychotherapy for methamphetamine use disorder: A pilot open-label safety and feasibility study
A single-arm, open-label pilot at an outpatient public stimulant treatment programme in Sydney, Australia enrolled fifteen adults who were seeking treatment for methamphetamine use.
Race/ethnicity moderates the associations between lifetime psilocybin use and opioid use disorder
Using National Survey on Drug Use and Health data from 2002 to 2019, covering 706,891 respondents, the author tested whether race and ethnicity change the reported link between lifetime psilocybin use and opioid use disorder.
Cessation and reduction in alcohol consumption and misuse after psychedelic use
A 2019 retrospective online survey (n=343 adults who had previously met criteria for alcohol use disorder and later had a psychedelic experience outside of treatment) reported changes in self-described drinking afterward.
Psilocybin-assisted treatment for alcohol dependence: A proof-of-concept study
A 2015 open-label proof-of-concept study (n=10) gave adults diagnosed with alcohol dependence oral psilocybin in one or two supervised sessions alongside Motivational Enhancement Therapy.
Psilocybin-Occasioned Mystical Experiences in the Treatment of Tobacco Addiction
A 2014 secondary analysis of the 15-participant open-label smoking-cessation pilot examined how the subjective quality of the psilocybin sessions related to outcomes.
OCD, headache, and eating disorders
A randomized clinical trial of repeated doses of psilocybin for the treatment of obsessive-compulsive disorder
A 2026 randomized controlled trial (n=15 participants with obsessive-compulsive disorder) compared psilocybin with an active placebo (lorazepam). According to Moreno and colleagues...
Psilocybin therapy for adult females with anorexia nervosa: pilot study
A single-blind within-individual pilot in 21 adult females with anorexia nervosa, who received three fixed-order oral psilocybin doses (1 mg, 25 mg, 25 mg) over six weeks alongside talk therapy and treatment as usual.
Safety, feasibility, and preliminary clinical outcomes of psilocybin-assisted therapy for veterans with severe, treatment-resistant PTSD: an open-label pilot clinical trial
An open-label pilot in 12 US military veterans with severe treatment-resistant PTSD, each receiving two synthetic psilocybin dosing sessions at 15 mg and 25 mg spaced two to three weeks apart, with roughly eight hours of therapy before and after.
Comparing single- and repeat-dose psilocybin with active placebo for migraine prevention in an exploratory randomized controlled clinical trial
Eighteen adults with at least two migraine days a week were randomised to two drug sessions held a week apart, receiving zero, one or two doses of psilocybin, with diphenhydramine given as an active placebo in any session without psilocybin.
Single-dose (10 mg) psilocybin reduces symptoms in adults with obsessive-compulsive disorder: A pharmacological challenge study
Nineteen adults with obsessive compulsive disorder of at least moderate severity each received two single oral doses of psilocybin in a fixed order, a very small dose first and a larger one four weeks later, in a day care facility staffed by clinicians experienced in psychedelic treatment.
Psilocybin therapy for females with anorexia nervosa: a phase 1, open-label feasibility study
A 2023 phase 1, open-label feasibility study (n=10 adult females with anorexia nervosa) reported on a single 25 mg dose of psilocybin given alongside psychological support.
Feasibility and Tolerability of Psilocybin for Phantom Limb Pain
A placebo-controlled, double-blind randomized pilot in nine people with one amputation and phantom limb pain, randomized to a single 25 mg oral dose of psilocybin (five participants) or 100 mg niacin (four). The authors report no emergent suicidality and no serious adverse...
'So many relationships in the room': Participant perspectives on the affordances and challenges of co-therapy in psychedelic assisted therapy
Eighteen participants sampled from a large randomised, open-label phase 2 trial of psilocybin-assisted therapy for generalised anxiety disorder gave 29 semi-structured interviews before and after their dosing sessions, and the transcripts were analysed thematically.
Acute and post-dosing effects of single-dose psilocybin for obsessive-compulsive disorder in a randomized, double-blind, placebo-controlled trial: an interpretative phenomenological analysis
Twelve people were interviewed about a month after psilocybin dosing in what the authors describe as the first randomised placebo-controlled trial of a single psilocybin dose with unstructured, non-directive support for treatment-refractory obsessive compulsive disorder.
Psilocybin pulse regimen reduces cluster headache attack frequency in the blinded extension phase of a randomized controlled trial
This 2024 paper reports the blinded extension phase (n=10) of a controlled cluster-headache study, in which participants could return for an open repeat of the three-dose psilocybin pulse regimen at least six months after their first round.
Pilot study of single-dose psilocybin for serotonin reuptake inhibitor-resistant body dysmorphic disorder
A 2023 open-label pilot trial (n=12 adults with body dysmorphic disorder unresponsive to serotonin reuptake inhibitors) tested a single 25 mg oral dose of psilocybin given with psychological support.
Exploratory investigation of a patient-informed low-dose psilocybin pulse regimen in the suppression of cluster headache: Results from a randomized, double-blind, placebo-controlled trial
A 2022 randomized, double-blind, placebo-controlled exploratory trial (n=14 analyzed) tested a patient-informed regimen of three low doses of psilocybin (0.143 mg/kg), given about five days apart, in people with cluster headache.
Exploratory Controlled Study of the Migraine-Suppressing Effects of Psilocybin
A 2021 double-blind, placebo-controlled cross-over study (n=10) tested a single oral dose of psilocybin (0.143 mg/kg) against placebo in people with migraine, tracking headaches for two weeks after each session.
Safety, tolerability, and efficacy of psilocybin in 9 patients with obsessive-compulsive disorder
A 2006 modified double-blind study (n=9 patients with obsessive-compulsive disorder) reported on up to four single doses of psilocybin per participant, ranging from sub-hallucinogenic to hallucinogenic, given in a controlled setting.
Hallucinogen-induced relief of obsessions and compulsions
A 1997 single-patient case report in the American Journal of Psychiatry (filed as a letter) describing a person with obsessive-compulsive disorder who, the authors report, experienced temporary relief of obsessions and compulsions after taking psilocybin-containing mushrooms.
How it acts on the brain
Psychedelics align brain activity with context
The authors report acquiring what they describe as the largest single-site psychedelic neuroimaging dataset to date.
Multi-metric evaluations of acute psychedelic effects on fMRI brain entropy
An independent test of the theory that psychedelics increase brain entropy, evaluating 14 entropy metrics drawn from thirteen prior studies in a 28-participant healthy cohort with 121 pre- and post-psilocybin fMRI scans, across two parcellation strategies and seven denoising pipelines.
A randomized crossover trial comparing the acute physiological and psychological effects of botanical formulations of oral psilocybin, oral psilocin, and sublingual psilocin
A randomized, within-subject crossover trial in 20 healthy adults (10 men, 10 women; mean age 40.1) comparing botanical whole-mushroom formulations across routes: oral psilocybin at 25 mg, oral psilocin at 17.5 mg, and sublingual psilocin at 2.18...
Psilocybin's effect on human brain synaptic plasticity
Fifteen healthy participants received a single 0.3 mg/kg dose of psilocybin either inside an MRI scanner or in a therapeutic-like room, with synaptic density measured via Synaptic Vesicle glycoprotein 2A using PET imaging in frontal cortex and hippocampus at baseline and one week after dosing.
Cognitive and subjective effects of psilocybin microdosing: Results from two double-blind placebo-controlled longitudinal trials
Two randomised, double-blind, placebo-controlled trials tested repeated low doses of psilocybin truffles taken over time in semi-naturalistic settings.
Psilocybin-induced changes in electroencephalography link acute and long-term effects
Twenty healthy participants, half of them women, took part in a double-blind, placebo-controlled crossover trial with high-density resting-state electroencephalography recorded at baseline and at one, three, six and twenty-four hours after dosing, with a further follow-up four weeks later.
The effects of psilocybin on time perception in humans: A comparative analysis of subjective and objective measures
Twenty-four healthy volunteers completed a double-blind, placebo-controlled comparison of how they judged the passage of time after psilocybin and after placebo.
Effects of Psilocybin on Religious and Spiritual Attitudes and Behaviors in Clergy from Various Major World Religions
Clergy from several major world religions, none of whom had taken a psychedelic before, were randomly assigned to two supported psilocybin sessions either straight away or after a waiting period.
Psilocybin desynchronizes the human brain
This 2024 study used dense, repeated brain scanning (precision functional mapping, roughly 18 MRI sessions per person) in a small group of healthy adults who received a 25 mg dose of psilocybin and, on a separate visit, the stimulant methylphenidate as a comparison.
Increased global integration in the brain after psilocybin therapy for depression
This 2022 study reanalyzed brain-scan (fMRI) data from two earlier trials of psilocybin for depression, including one open-label trial and one randomized trial comparing psilocybin with the antidepressant escitalopram.
Psilocybin induces rapid and persistent growth of dendritic spines in frontal cortex in vivo
This 2021 mouse study used two-photon microscopy to watch individual brain-cell connections over time.
Classic psychedelics: An integrative review of epidemiology, therapeutics, mystical experience, and brain network function
This 2019 review from the Johns Hopkins group draws together four strands of classic-psychedelic research: population surveys on use and outcomes, early-phase clinical trials across several conditions, the role of subjective 'mystical-type' experience...
Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels
In this 2019 study, researchers gave healthy volunteers single oral doses of psilocybin (ranging from about 3 to 30 mg) and used PET brain scans plus blood samples to track what was happening in the body.
REBUS and the Anarchic Brain: Toward a Unified Model of the Brain Action of Psychedelics
A 2019 theoretical review in Pharmacological Reviews (vol 71, issue 3, pp 316-344) proposing the 'REBUS' model, Relaxed Beliefs Under pSychedelics, which combines the entropic-brain hypothesis with Karl Friston's free-energy principle.
Quality of Acute Psychedelic Experience Predicts Therapeutic Efficacy of Psilocybin for Treatment-Resistant Depression
This 2018 Imperial College London analysis (Frontiers in Pharmacology, 8:974) drew on an open-label study in which 19 people with treatment-resistant depression received two doses of psilocybin with psychological support.
Psychedelics Promote Structural and Functional Neural Plasticity
This 2018 laboratory study tested several psychedelic compounds in rodent and fruit-fly models and in cultured neurons.
Psilocybin for treatment-resistant depression: fMRI-measured brain mechanisms
In this 2017 open-label study, researchers used fMRI to scan the brains of patients with treatment-resistant depression before and one day after two doses of psilocybin (usable imaging data from 16 of 19 participants). The authors reported decreased blood flow in the amygdala...
Patients' Accounts of Increased "Connectedness" and "Acceptance" After Psilocybin for Treatment-Resistant Depression
A 2017 qualitative study (Journal of Humanistic Psychology, vol 57, pp 520-564) drawn from the Imperial College open-label trial of psilocybin for treatment-resistant depression.
Psychedelics
This 2016 review by pharmacologist David E. Nichols is a widely cited, book-length survey of the serotonergic psychedelics, including psilocybin, LSD, mescaline and DMT.
The entropic brain: a theory of conscious states informed by neuroimaging research with psychedelic drugs
This 2014 'Hypothesis and Theory' paper by Carhart-Harris and colleagues draws on psilocybin neuroimaging data to propose the 'entropic brain' hypothesis: that the richness of a conscious state can be indexed by the measurable entropy, or disorder, of spontaneous brain activity.
Prediction of psilocybin response in healthy volunteers
A pooled analysis of data from 23 controlled laboratory studies, covering 409 psilocybin administrations to 261 healthy volunteers, examining which factors predict the acute response.
Factor Analysis of the Mystical Experience Questionnaire: A Study of Experiences Occasioned by the Hallucinogen Psilocybin
A 2012 psychometric study that analyzed questionnaire data from 1,602 people who had taken psilocybin and reported a 4-factor structure underlying classic mystical-type experiences: unity/noetic quality/sacredness, positive mood, transcendence of time and space, and ineffability.
Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin
In this 2012 fMRI study, researchers led by Carhart-Harris scanned two groups of healthy volunteers (15 and 15) before and after they received intravenous psilocybin.
Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects
A double-blind, dose-escalation study in which 18 healthy, mostly hallucinogen-naive adults each received five sessions with placebo or psilocybin at ascending or descending doses (0, 5, 10, 20...
Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance
A 2006 Johns Hopkins double-blind study had 36 hallucinogen-naive healthy adults receive a high dose of psilocybin and a comparison drug (methylphenidate) under supportive conditions, in counterbalanced order.
Psilocybin induces schizophrenia-like psychosis in humans via a serotonin-2 agonist action
A 1998 human study by Vollenweider and colleagues tested which receptor drives psilocybin's psychoactive effects.
CSF galanin and noradrenaline downregulation by psilocybin therapy in major depressive disorder
A secondary analysis of a randomised, placebo-controlled trial of psilocybin in major depressive disorder, using biomarkers measured in both cerebrospinal fluid and blood.
Effects of psilocybin on personality, psychiatric symptoms, and values: Exploring mediating effects of the acute psychedelic experience
This secondary analysis drew on a phase 1, double-blind, randomised, placebo-controlled trial in 89 healthy participants, who received one of two active doses of psilocybin or an inert placebo.
Participant Experiences of Therapeutic Touch in Psilocybin-Assisted Therapy
Eighteen participants in a large randomised trial of psilocybin-assisted therapy that permitted protocol-defined supportive touch gave 39 semi-structured interviews before and after dosing, covering what they expected of touch, what they experienced and how they read it afterwards.
Trip sitting or just sitting? Session facilitators substantially influence psychedelic experiences in clinical trials but not in healthy ones
This analysis pooled data from nine psilocybin administration studies covering 298 participants, 670 dosing sessions and 60 facilitators, which the authors describe as the largest dataset of its kind.
Pilot study comparing the effects of high dose THC to high dose psilocybin and placebo in the set and setting of a classic psychedelic therapy session
A double-blind, placebo-controlled, within-subject crossover pilot run at Johns Hopkins under the set and setting conditions of a typical psychedelic clinical trial session.
Enhanced meaning in life following psychedelic use: converging evidence from controlled and naturalistic studies
This paper brings together three sets of data on meaning in life, all measured with the Meaning in Life Questionnaire: a randomised clinical trial of psilocybin for depression, a single-arm study of controlled psilocybin administration in healthy volunteers...
Homological scaffolds of brain functional networks
In this 2014 study, Petri and colleagues applied topological data analysis to fMRI scans from healthy volunteers who received either placebo or intravenous psilocybin.
Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personality domain of openness
This 2011 Johns Hopkins study (Journal of Psychopharmacology, 25(11):1453-1461) analyzed data from healthy adults who received psilocybin and placebo-like comparison doses under supportive conditions across multiple sessions.
Mystical-type experiences occasioned by psilocybin mediate the attribution of personal meaning and spiritual significance 14 months later
This 2008 Johns Hopkins follow-up (Journal of Psychopharmacology, 22(6):621-632) revisited healthy adult volunteers roughly 14 months after they received psilocybin under supportive conditions in an earlier double-blind study.
Safety and adverse events
Hallucinogen-Psychosis Associations Are Confounded by Baseline Psychiatric History
A retrospective analysis of MarketScan Medicaid and commercial claims from 2015 to 2019 covering 273,466 individuals with substance-related emergency admissions or hospitalizations.
Psychedelics stores, their regulation and public health: knowledge, perceptions, attitudes and opinions of Canadians
A web survey of 3,674 Canadian adults conducted in March 2025, examining what Canadians know and think about the psychedelic retail stores that have proliferated in Canada, close to 60 documented storefronts in 2023, selling psilocybin and DMT outside the law.
Cardiovascular safety of psilocybin in psychiatric practice: a narrative review
A structured narrative review, searched through 10 July 2026, translating cardiovascular evidence into a risk-stratified framework for psychiatric practice.
A cross-national comparison of nonmedical and medical use of psychedelic drugs in the international cannabis policy study
The 2023 International Cannabis Policy Study asked respondents in Canada, the United States, Australia and New Zealand about lifetime, past-year and past-month use of psilocybin, LSD, MDMA and ketamine, whether they had discussed such use with a medical professional...
Effects of psychedelic use on authoritarian attitudes revisited
The authors revisited the claim that psychedelic use lowers authoritarian attitudes, drawing on three studies with different designs and populations.
Impact of Psilocybin on Motor Function in Healthy Participants: A Phase 1, Randomised, Triple-Blind, Dose-Finding Study
Thirteen healthy adults with a median age of 33 took part in a Phase 1 randomised, triple-blind study asking whether movement tasks can be carried out while psilocybin is active.
Psilocybin microdosing in the United States: Insights from a nationally representative survey
A probability-based national survey of US adults, fielded from December 2023 to January 2024, asked about psilocybin microdosing, meaning taking a fraction of a full dose.
Safety and Mental Health Outcomes of Oregon State-Regulated Psilocybin Services
A cohort study enrolled 346 clients of Oregon's regulated psilocybin services between November 2024 and March 2026, at 24 of the 26 centres then licensed, with sessions supervised by 83 licensed facilitators.
Trends in first-time psychedelic and other hallucinogen use in the United States: Results from the National Survey on Drug Use and Health
An analysis of the National Survey on Drug Use and Health, a repeated cross-sectional survey of US residents aged 12 and older, tracked how often people reported using a hallucinogen for the first time in the past year.
U.S. Psychedelic Use and Microdosing in 2025: Insights from a Probability-Based and Nationally Representative Survey
A probability-based, nationally representative US survey reporting prevalence of use across 11 psychedelic substances, with detailed estimates for microdosing of psilocybin, LSD and MDMA.
Unequal representation? A cross-sectional analysis of age, sex, race, and ethnicity in clinical trials of classic psychedelics
Two reviewers worked independently through the interventional studies of classic psychedelics listed on ClinicalTrials.gov up to January 2025, keeping phase 2 to 4 trials in psychiatric conditions, to see who had taken part in them.
Acute Adverse Effects of Therapeutic Doses of Psilocybin: A Systematic Review and Meta-Analysis
A 2024 systematic review and meta-analysis of six randomized, double-blind trials (528 participants treated for depression or anxiety, including major depressive disorder, treatment-resistant depression...
Adverse Events in Studies of Classic Psychedelics: A Systematic Review and Meta-Analysis
A 2024 systematic review and meta-analysis pooling 114 studies (3,504 participants) examined how often adverse events were reported across classic-psychedelic research.
Survey study of challenging experiences after ingesting psilocybin mushrooms: Acute and enduring positive and negative consequences
A 2016 anonymous online survey (n=1,993) in which respondents recalled their single most psychologically difficult or challenging experience after taking psilocybin mushrooms.
Classic psychedelic use is associated with reduced psychological distress and suicidality in the United States adult population
A 2015 cross-sectional study pooling five years of the US National Survey on Drug Use and Health (2008-2012), covering over 190,000 adults.
Psychedelics not linked to mental health problems or suicidal behavior: A population study
An observational analysis of a U.S. National Survey on Drug Use and Health sample of 135,095 adults, including roughly 19,300 who reported lifetime use of a classic psychedelic.
Acute, subacute and long-term subjective effects of psilocybin in healthy humans: a pooled analysis of experimental studies
A 2011 pooled analysis combining eight double-blind, placebo-controlled experiments (110 healthy volunteers, studies run 1999-2008) to characterize psilocybin's acute, short-term and long-term subjective effects.
Human hallucinogen research: guidelines for safety
A methods and safety review by Johns Hopkins researchers that proposes widely cited guidelines for conducting human studies with hallucinogens such as psilocybin.
Assessing The Readiness of Psychiatrists in Louisiana to Incorporate Psilocybin into Clinical Practice-Lessons Learned from a State Underrepresented in Clinical Psychedelic Research
A thirty-question survey was mailed and sent by digital newsletter to registered psychiatrists in Louisiana, asking how strongly they agreed with statements about psilocybin research, legalization, safety, addiction potential and medical use.
Attitudes Toward Psychedelic Treatments by Individuals With Histories of Substance Use or Psychiatric Disorders: A Survey Study
At a large tertiary hospital, a cross-sectional survey ran between June 2023 and February 2024, recruiting English-speaking adults with alcohol use disorder, opioid use disorder or psychiatric disorders through the patient portal, inpatient floors and flyers.
Classic psychedelic and cannabis use among U.S. cancer survivors aged ≥ 50 years: nationally representative estimates by cancer type/site
A pooled analysis of National Survey on Drug Use and Health data compared lifetime cannabis and classic psychedelic use among US adults aged 50 and over, with and without a history of cancer.
Expectations and Motivations for Participation in Clinical Trials Utilizing Psychedelics for Treatment-Resistant Depression: A Qualitative Study
Seventeen people were interviewed before screening for two trials at a German university hospital, one using 5-MeO-DMT and one using psilocybin for treatment-resistant depression, with two of them interviewed again afterwards.
From trials to clinics: investigators' perspectives on translating psychedelic research into clinical care
Semi-structured interviews with 21 clinical investigators at major US academic psychedelic research centres asked how they expect treatments such as psilocybin and MDMA to move out of trials and into ordinary clinical care.
Global Trends in Psychedelic Microdosing: Demographics, Substance Testing Behavior, and Patterns of Use
An online survey of 6,193 people who use psychedelics, 2,488 of them microdosers, compared people who only microdose with people who take both micro and full doses.
Implementing psilocybin-assisted therapy in palliative care settings: A survey of stakeholders
A cross-sectional online survey, open between April and December 2024, asked people working in Canadian palliative care what they knew and thought about psilocybin-assisted therapy for existential distress.
Inaugural year of regulated psilocybin services in Oregon: safety, motivations, and utilization
A descriptive analysis of aggregate statewide data published on the Oregon Psilocybin Services dashboard, covering a full calendar year of the first statewide regulated psilocybin framework in the United States.
Microdosing psychedelics: What, why, when, and how often? Insights from an international survey of people who use psychedelics
The Global Psychedelic Survey 2025 ran online in nineteen languages for three weeks in May 2025 and asked about psychedelic use; this paper covers the microdosing answers.
Patient perspectives on research gaps in cluster headache
An online survey recruited Australian adults with self-reported cluster headache through clinicians, patient advocacy groups and social media, asking about treatment experience and what research they want.
Perceptions of Psilocybin-Assisted Psychotherapy and Standard Interventions for Nicotine Cessation
An online survey of 534 adults who used nicotine daily asked how they viewed psilocybin-assisted psychotherapy for quitting, alongside standard cessation treatments.
Preferences, Perceptions, and Environmental Considerations of Natural and Synthetic Psychedelic Substances: Findings from the Global Psychedelic Survey
An anonymous online survey collected answers from 6,379 people who use psychedelics across 85 countries about where they prefer their substances to come from.
Provider perspectives on challenges in treatment during psychedelic therapy
An anonymous survey went by email to contacts listed on ClinicalTrials.gov for psilocybin and LSD trials, to the authors' own contacts and onward through snowball sampling, asking what goes wrong during psychedelic sessions.
Psychedelic Use, Microdosing, Motives, and Information and Product Sources Among Young Adults in the United States
In 2025 an online survey of 3,227 US adults aged 18 to 34, about half of whom used cannabis in the past month by design, asked about psychedelic use, microdosing and reasons for using.
Substance use predictors of arrest and self-reported criminal behavior in the United States: The role of psychedelics and rarely used drugs
Using National Survey on Drug Use and Health data from 2014 to 2023, covering 544,740 respondents, the author ran logistic regressions testing whether reported drug use predicted arrests and self-reported crime.
"Wood-lover paralysis": Describing a toxidrome with symptoms of weakness caused by some lignicolous "wood-loving" Psilocybe mushrooms
A retrospective online survey run in 2020 collected accounts of transient weakness after eating psilocybin mushrooms from wood-loving Psilocybe species, a pattern the authors call wood-lover paralysis.
Best practices for first psychedelic experiences: harm reduction advice from the psychedelic community
An online survey asked 581 people who use psychedelics what they would tell someone taking one for the first time, following a community-based collaborative approach, with open-ended answers coded by a qualitative researcher and two coders.
Characteristics and mental health of psychedelic mushroom and multi-psychedelic users relative to non-psychedelic users in American adults, 2020-2021
Acumen Health Research Institute ran a cross-sectional survey of American adults that compared people who used psychedelic mushrooms only, people who used mushrooms alongside other psychedelics, and people who used no psychedelics.
Characteristics of Ongoing Clinical Trials of Psychogenic Substances for Psychiatric Disorders
A cross-sectional analysis characterised NIH-registered trials of psychogenic substances for psychiatric conditions that were ongoing in late 2024, defining such substances as compounds that significantly affect perception, cognition or emotion.
Examining differences in the effects and contexts of naturalistic psilocybin use for White participants vs. Participants of Color: A longitudinal online survey study
An online longitudinal survey followed 2,833 people who planned to use psilocybin outside a clinical setting, comparing White participants with Participants of Color, the terms the authors use.
Geographical Differences in Self-Reported Past 12-Month Drug Use: Results from the NDEWS Rapid Street Reporting, 2021-2023
The National Drug Early Warning System's Rapid Street Reporting study interviewed adults in public places across 20 US cities over single weekends between January 2022 and November 2023, asking what they had used in the past twelve months.
Informed Consent Documents from Psychedelic Clinical Trials: A Descriptive Ethical Analysis
The authors gathered the consent documents handed to participants in US psilocybin trials and read them against the proposals psychedelic bioethicists have made for what such documents should contain.
Latent Classes of Lifetime Use of Seven Hallucinogens in the United States
A latent class analysis of 2021 and 2022 National Survey on Drug Use and Health data, restricted to the 17,977 respondents who reported ever using a hallucinogen, looked for patterns in which substances people had used.
Patients' Attitudes Toward Hallucinogenic and Non-Hallucinogenic Psilocybin for Mental Health Treatment
A cross-sectional survey at a community mental health centre asked psychiatric patients aged 18 to 65 what they knew about psilocybin therapy and whether they would accept it, in both hallucinogenic and non-hallucinogenic forms.
Perspectives on Trauma Treatment, Self-Management Strategies, and Attitudes Toward Psychedelic Therapies in Individuals with Psychological Trauma Symptoms
An online survey recruited people who reported trauma symptoms or carried a diagnosis of post-traumatic stress disorder or its complex form, and asked about their treatment history, how satisfied they were, and whether they used illicit substances to manage symptoms.
Psilocybin Dispensaries and Online Health Claims in Canada
Working from systematic web searches and media reports, the authors mapped the psilocybin dispensaries trading in Canada during May 2024, then read what those stores claimed online.
Regulatory Alignment of Psilocybin Clinical Trials in Major Depressive Disorder on ClinicalTrials.gov: A Cross-Sectional Analysis
A cross-sectional review searched ClinicalTrials.gov for interventional studies of psilocybin and psilocin that had posted their protocols, keeping those in major depressive disorder and treatment-resistant depression.
The Role of Touch in Psychedelic Therapy: Perspectives From a Survey of Practitioners in Research Settings
A survey of practitioners in psilocybin and LSD research settings, distributed by email through ClinicalTrials.gov contacts, the authors' own contacts and snowball sampling, asked where physical touch belongs in psychedelic therapy.
Reviews and meta-analyses
Blinding Integrity in Psychedelic Randomized Clinical Trials: A Systematic Review
A PRISMA systematic review of 112 randomized controlled trials of psychedelics as psychiatric interventions, comprising 11 psilocybin, 17 LSD, 78 ketamine, 11 MDMA, 2 ayahuasca, 2 DMT and 1 noribogaine, searched to 11 December 2025. Only 29.5% assessed blinding integrity...
Efficacy and Safety of Psychedelic Microdosing on Psychological Outcomes in Healthy Adults: A Systematic Review and Meta-analysis
A PROSPERO-registered systematic review and meta-analysis of 24 studies covering 3,681 participants, searching Embase, MEDLINE and PsycINFO to February 2026 for sub-hallucinogenic dosing in healthy adults.
Efficacy and safety of psychedelics for the treatment of mental disorders: A systematic review and meta-analysis
This 2024 systematic review and meta-analysis pooled 126 included articles covering several classic and related psychedelics (psilocybin, LSD, ayahuasca...
Efficacy of psilocybin for treating symptoms of depression: systematic review and meta-analysis
This systematic review and meta-analysis pooled randomized trials comparing psilocybin against control conditions for depressive symptoms.
Efficacy and acceptability of psilocybin for primary or secondary depression: A systematic review and meta-analysis of randomized controlled trials
This 2024 meta-analysis pooled 8 randomized controlled trials covering 524 adults with primary or secondary depression.
Psychedelic therapy for depressive symptoms: A systematic review and meta-analysis
This 2023 systematic review examined fourteen psychedelic-therapy studies using psilocybin, ayahuasca, or LSD, with seven randomized trials carried forward into the meta-analysis.
Classic serotonergic psychedelics for mood and depressive symptoms: a meta-analysis of mood disorder patients and healthy participants
This 2021 meta-analysis pooled 12 randomized, double-blind trials (257 participants in total: 124 healthy volunteers and 133 people with mood disorders) of classic serotonergic psychedelics, namely psilocybin, LSD and ayahuasca.
Efficacy of psychedelic treatments on depressive symptoms: A meta-analysis
This 2020 meta-analysis pooled eight studies of serotonergic psychedelic (5-HT2A agonist) treatments and their effect on depressive symptoms.
Psilocybin as a New Approach to Treat Depression and Anxiety in the Context of Life-Threatening Diseases-A Systematic Review and Meta-Analysis of Clinical Trials
This 2020 systematic review with meta-analysis pooled three randomized controlled trials (n=92), most involving patients with advanced cancer, to assess psilocybin's effect on depression and anxiety.
A Meta-Analysis of Placebo-Controlled Trials of Psychedelic-Assisted Therapy
This 2020 meta-analysis identified nine randomized, placebo-controlled trials of psychedelic-assisted therapy published since 1994, covering psilocybin, LSD, ayahuasca, and MDMA.
The experimental effects of psilocybin on symptoms of anxiety and depression: A meta-analysis
This 2020 meta-analysis pooled four studies (117 participants total), three of which were randomized and placebo-controlled, to examine psilocybin's reported effects on anxiety and depression symptoms.
Classical psychedelic microdosing, mood, and cognitive function: An umbrella review with narrative synthesis
An umbrella review of systematic reviews and meta-analyses of microdosing, defined as 20 micrograms of LSD or 3 mg of psilocybin per session or less, searched across six databases to February 2026. Three meta-analyses met quantitative criteria...
Subacute and long-term changes in cognitive functioning after administration of classic psychedelics, MDMA and ketamine: A systematic review of clinical and preclinical evidence
A systematic review of subacute and long-term effects, one day or more after dosing, of classic and non-classic psychedelics on executive function, attention and decision-making, drawing on 67 articles, 47 clinical and 20 preclinical, from MEDLINE, EMBASE, PsycInfo and Web of Science.
The early studies, 1958 to 1991
Pahnke's "Good Friday Experiment": A Long-Term Follow-Up and Methodological Critique
A 1991 long-term follow-up published in the Journal of Transpersonal Psychology.
Implications of LSD and Experimental Mysticism
A 1966 theoretical paper in the Journal of Religion and Health in which Pahnke and Richards proposed a nine-category typology for describing mystical experience.
Drugs and Mysticism: An Analysis of the Relationship between Psychedelic Drugs and the Mystical Consciousness
This 1963 Harvard doctoral dissertation (a thesis, not a journal article) documents the double-blind 'Good Friday' or Marsh Chapel Experiment that Walter Pahnke conducted in 1962. Twenty divinity students received either psilocybin or an active placebo during a religious service.
Psilocybin, ein psychotroper Wirkstoff aus dem mexikanischen Rauschpilz Psilocybe mexicana Heim
This 1958 report in Experientia is the foundational chemical-identification paper for psilocybin.
For educational purposes only. Each summary reports what the cited study found and is not medical advice or an endorsement. This site makes no medical claims about psilocybin.