Psilocybin: what the research shows

The compound, the product and the setting

In a trial, psilocybin can be a precisely defined synthetic drug. “Magic mushrooms” may refer to several species, and the amount of psilocybin can vary. Mushrooms can also be misidentified or contaminated.

A trial specifies the product, preparation, support and monitoring. These controls are not present in every setting. A mushroom product’s name does not establish its strength, purity or equivalence to a trial drug. This profile explains research; it does not provide instructions for taking psilocybin. See also microdosing and the evidence and stress and mood.1

What happens in the body

The body converts psilocybin to psilocin. Psilocin affects serotonin signalling and can change perception, mood, thought and the sense of self.

Knowing how a compound affects the brain does not establish whether it is a safe or effective treatment, or how long a benefit might last. A person’s health, expectations, other care and psychological support also matter. A subjective experience alone is not an established measure of improvement in depression, addiction or daily functioning. Those claims need measures chosen in advance and studied in people.110

Evidence depends on the condition and protocol

Researchers have studied psilocybin with psychological support for depression, alcohol and tobacco use disorders, anxiety associated with serious illness, and other questions. Studies differ in who takes part, what treatment is used for comparison, what support is given and how long people are followed.

A result in people with treatment-resistant depression does not automatically apply to people with a first episode of depression, healthy volunteers or people with a different substance-use condition. Psychedelic trials can also be hard to blind: the effects may let participants or staff guess which treatment was given, affecting expectations and reported results. The 2022 study page is one historical example, not a review of all the evidence. See also psilocybin and smoking cessation.27

Safety belongs in the main explanation

Short-term effects can include intense perceptual and emotional changes, anxiety, headache, nausea, dizziness and impaired judgement. The US National Center for Complementary and Integrative Health (NCCIH) warns that effects are unpredictable and can be serious. It says psilocybin is not considered safe for people with psychotic conditions or severe forms of bipolar disorder. These cautions are psilocybin-specific; they should not be generalized automatically to MDMA, ketamine, LSD or ibogaine. Case reports and a literature review have described hallucinogen persisting perception disorder, a condition involving continuing perceptual symptoms. The evidence does not establish how often it occurs or whether a risk estimate from a trial applies more widely. Screening and monitoring in research reduce risk but also limit generalisability. A low event rate in a selected trial cannot rule out uncommon or delayed harms in a much larger or less screened population.

If someone may have swallowed an unidentified or poisonous mushroom, contact a local poison service or emergency service immediately, even if they seem well: symptoms of some dangerous poisonings can be delayed. If the person collapses, has a seizure, has trouble breathing or cannot be awakened, call emergency services immediately. Take the packaging or information about what was eaten if available, and follow the responding service’s instructions.1782122

One depression trial, read with its caveats

The 2022 COMPASS phase 2 trial illustrates why the product, support and people studied matter. At three weeks, people assigned 25 mg improved more on a clinician-rated depression scale than those assigned 1 mg. The scale is called the Montgomery–Åsberg Depression Rating Scale (MADRS).

The study’s testing plan stopped further confirmatory testing after the 10-mg comparison did not reach statistical significance. A sustained response at week 12 was not statistically established. Adverse events, including suicidal thoughts or self-injury, occurred in all dose groups; reporting an event does not by itself show what caused it.

The trial excluded people judged to be at clinically significant risk of suicide. Participants had limited ethnic diversity, and the noticeable effects may have made it easier to guess the treatment. The report discloses the sponsor’s roles in design, funding, review and interpretation, as well as contracted analysis and writing assistance. Additional details in the journal supplement have not been assessed here.341516

Approval, access and research are separate questions

The FDA’s guidance on psychedelic clinical trials explains how sponsors can study these drugs; issuing guidance does not itself approve psilocybin. Approval depends on the specific medicine, condition and jurisdiction. National laws, research permissions and exceptional-access arrangements can change, so check the regulator for the country concerned. A trial registration, a developer announcement or a local programme does not create a general treatment authorisation. A regulator may require evidence about manufacturing, abuse potential, psychological support, durability and post-authorisation monitoring before deciding on a product.75

A US depression trial in 2023

A 2023 Usona-sponsored phase 2 trial studied 104 adults at 11 US sites. Participants received either 25 mg psilocybin or niacin, with psychological support. On the MADRS depression scale, the difference between groups was −12.3 points at day 43 and −12.0 points at day 8.

The report found no serious treatment-emergent adverse events, but it reported more adverse events overall, and more severe events, with psilocybin. “Severe” describes intensity; “serious” uses separate criteria, such as hospitalisation or a life-threatening event.

The authors acknowledged that noticeable effects may have helped participants guess their treatment, even though central raters assessed outcomes. Usona sponsored the study and was involved in design, analysis, interpretation and writing. Only 12.5% of participants met the study’s definition of treatment-resistant depression, so the findings do not answer every question about depression.1123

EPIsoDE: a German trial in 2026

The 2026 German EPIsoDE trial randomized 144 adults with treatment-resistant depression to treatment sequences beginning with 25 mg psilocybin, 5 mg psilocybin or nicotinamide, with psychotherapy. At six weeks, before a second dose, researchers looked for a reduction of at least half on a depression scale. This was seen in 8 of 47 people (17.0%) in the 25-mg group, 6 of 48 (12.5%) in the 5-mg group and 5 of 47 (10.6%) in the nicotinamide group. The main comparison, chosen in advance, was 25 mg versus nicotinamide. It did not meet the trial’s primary goal. Other, exploratory analyses found larger average symptom-score changes with 25 mg, but formal testing stopped after the main comparison.

Two serious adverse reactions were reported after 25 mg, including one case of persistent perceptual symptoms diagnosed as hallucinogen persisting perception disorder. Most participants correctly identified the 25-mg dose, limiting the blind. German federal research funding supported the trial; the report says funders had no role in its conduct or reporting.14

A Stockholm study with one-year follow-up

A 2026 study at one Stockholm site involved 35 people. Researchers found a difference on the MADRS depression scale at day 8, the main point they had chosen to measure. At day 365, the difference was no longer statistically significant.

Most participants could tell which treatment they received: at day 365, 16 of 17 in the psilocybin group and all 16 assessed in the niacin group guessed correctly. Two people in the psilocybin group had persistent severe anxiety that needed medical attention.

Norrsken Mind and Swedish Research Council grants supported the study. Usona supplied the study drug, treatment manual and training. The report says funders had no role in the design, conduct, analysis or submission.12

The 2026 NHS feasibility trial

A 2026 NHS single-site feasibility trial screened 75 people with treatment-resistant depression, randomized 60 to psilocybin or placebo with psychological support, and retained 59 for all depression-scale follow-ups. The main goal was to see whether the study was practical to run. Its main outcomes did not measure whether the treatment worked. At three weeks, the psilocybin group’s adjusted score on the MADRS depression scale was 10.41 points lower than placebo on average, and the difference persisted at six weeks. The placebo group showed little average improvement. This is a promising secondary finding in a small trial. It does not predict what will happen to an individual or prove a lasting benefit. When a subset was asked to guess their assignment, all who received psilocybin and 70% of those given placebo guessed correctly; expectations may have affected the comparison.

The study recorded 287 nonserious adverse-event reports (164 psilocybin, 123 placebo; counts of events, not affected people) and four serious events across trial phases: one placebo-arm event and three in participants who received psilocybin. Investigators judged the latter unrelated to treatment. COMPASS supplied COMP360 and matching placebo; the NHS and King’s College London sponsored the study, and the report says the supplier had no role in its design, conduct or analysis. These supervised research results are not a direct comparison with standard care, an approval or a self-treatment recommendation.13

How did psilocybin compare with an antidepressant?

In a 2021 UK phase 2 trial, 59 adults with depression were randomly assigned to a psilocybin-based programme or the antidepressant escitalopram, with psychological support in both groups. The escitalopram group also received a low dose of psilocybin in the trial. At six weeks, the average change on the primary self-reported depression scale was −8 points with psilocybin and −6 with escitalopram; the difference was not statistically significant. A small inconclusive trial does not prove that the treatments are equally effective, nor does it establish that one is superior. Other measures often favoured psilocybin. However, the comparisons were not adjusted for the number of outcomes tested, which makes chance findings more likely. The groups had different treatment schedules, and the noticeable psychedelic effects make the results harder to interpret. In an observational six-month follow-up, 25 of 30 people in the psilocybin group and 21 of 29 in the escitalopram group completed follow-up; participants could receive other care after the initial trial. The longer-term comparison therefore cannot isolate the initial treatments. The original university-sponsored trial was supported by a charitable donation and founding partners, with public research infrastructure; COMPASS Pathways supplied psilocybin, and several authors disclosed industry relationships. Do not change prescribed antidepressants without clinical advice. For another depression study, see the 2022 trial explainer.1920

What about alcohol use disorder?

Research has produced encouraging but mixed results. A 2022 US trial assigned 95 adults with alcohol use disorder to psilocybin or another medicine, diphenhydramine. Both groups also received a structured psychotherapy programme. Of the 95 people, 93 received the study medicine and were included in the main analysis. Over the 32-week assessment period, heavy-drinking days accounted for 9.7% of days in the psilocybin group and 23.6% in the comparison group. The study relied on people reporting their drinking. The noticeably different drug effects could also make it difficult to keep participants and staff unaware of which treatment was given. A 2025 Swiss trial tested a different programme after withdrawal treatment: 37 participants completed the four-week assessment, and researchers did not find a statistically significant difference in its primary alcohol-use outcomes. This smaller study cannot rule out a benefit. The populations, comparison medicines, number of sessions and psychotherapy differed, so the results are not direct replicas. Neither establishes that mushrooms or unsupervised use treat alcohol problems; existing care and withdrawal support can be discussed with a clinician.1718

What a responsible conclusion sounds like

Researchers have studied defined psilocybin products in selected groups, under controlled conditions and with support. Some results are promising, but important questions about benefit, safety and duration remain.

An early trial or a theory about how psilocybin works does not show that it is safe or effective for everyone. Larger comparison trials, longer follow-up and better reporting of harms may help answer the remaining questions.7

Keep the support package visible

In a trial, preparation before a session, supervision during it and follow-up afterwards may all be part of the treatment being studied. A headline that names only the drug can hide this support and the safety procedures.

That does not prove the support caused the benefit. It means the results should describe the whole package tested, rather than suggest the drug was studied on its own.7

A five-question reader check

Is the source talking about a defined psilocybin product, mushrooms or a broader therapy? Who was studied, for which condition, and who was excluded? What was the treatment compared with, and what support did people receive? What did researchers measure, and for how long? What harms were recorded and what is still unknown?

This page is educational. It does not provide dosing, treatment or legal advice.

Development & regulatory context

These selected records are not a complete global legal-status list. Approval depends on the product, use, population and country; check each record’s date.