Evidence

What the clinical trials found.
Sources linked, limits stated.

I keep this index so you can read the studies yourself. Each entry says who was studied, what the trial found and what it did not show. It is for informed decision-making, not medical advice.

Curated studies

Deep dives by condition

Where the field stands

Psilocybin research began in the 1950s and 1960s with promising early results in addiction, depression, and end-of-life anxiety. Criminalization under the Controlled Substances Act in 1970 halted almost all clinical work for three decades. Research restarted in the 2000s, when Johns Hopkins University received US authorization for a psilocybin study (Griffiths et al., 2006) and Imperial College London began studies under UK regulation.

Since 2000, the field has accumulated peer-reviewed evidence across several conditions, much of it from small trials. As of October 2026, COMPASS Pathways has reported two phase 3 trials in treatment-resistant depression (sponsor-reported) and Usona Institute has completed enrollment in a phase 3 trial in major depressive disorder. No psilocybin product is FDA-approved.

FDA granted Breakthrough Therapy designation to COMPASS Pathways' psilocybin (COMP360) for treatment-resistant depression in October 2018 and to Usona Institute's psilocybin for major depressive disorder in November 2019. The designation is an expedited review pathway for those sponsors' products in development. It is not approval of psilocybin or of any setting.

Psilocybin is a naturally occurring indole alkaloid found in approximately 200 species of fungi worldwide. In the body it converts to psilocin, which acts as a partial agonist at serotonin 2A receptors (5-HT2A), particularly in the prefrontal cortex. Onset is typically 20 to 40 minutes after oral ingestion, with a peak at 90 to 120 minutes and a total duration of 4 to 6 hours.

Further reading

The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma, van der Kolk, Bessel, Viking, 2014. A trade book that synthesizes trauma research and clinical practice. Read it as an introduction to the field, not as a study.

Want to read a study the way I do? How we read a study. Prefer the explainers? Start at the science hub.

Inclusion criteria

Studies included in this index are peer-reviewed, conducted as randomized controlled trials or open-label trials, have a sample size of at least 10 participants, and are published in an indexed journal. We review and update this index periodically as new research is published. The few mouse, imaging and microdosing entries are labeled by condition so you can tell them apart.