Phase 1 trial suggests benefit of psilocybin in OCD treatment
The Brown University Psychopharmacology Update June 28, 2026 DOI: 10.1002/pu.31474 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Phase 1 trial Peer reviewed |
|---|---|
| Sample size | 15 |
| Population | Patients with obsessive-compulsive disorder |
| Intervention | Psilocybin |
| Dose | high-dose, low-dose |
| Topics | Psilocybin |
| Keywords | Placebo Adverse effect Hallucinogen Clinical trial Pharmacology Phase matter Double blind |
| Key findings | Repeated high-dose administration of psilocybin was more effective than low-dose psilocybin or placebo in reducing OCD symptoms. |
Abstract
A Phase 1 trial comprising 15 patients has found that repeated high‐dose administration of psilocybin was more effective than low‐dose psilocybin or placebo in reducing symptoms of obsessive‐compulsive disorder (OCD). Psilocybin was generally well‐tolerated, with no reports of serious adverse events.
Comparable studies
Other non-randomized and open-label trials on psilocybin, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Psilocybin with psychological support for treatment-resistant depression: an open-label feasibility study. Patients with moderate-to-severe, unipolar, treatment-resistant major depression | 2016 | Open-label feasibility trial | n = 12 |
| Psilocybin with psychological support for treatment-resistant depression: six-month follow-up. Patients with severe, unipolar, treatment-resistant major depression | 2017 | Open-label trial | n = 20 |
| Pilot study of the 5-HT2AR agonist psilocybin in the treatment of tobacco addiction Psychiatrically healthy nicotine-dependent smokers | 2014 | Open-label pilot study | n = 15 |
| Quality of Acute Psychedelic Experience Predicts Therapeutic Efficacy of Psilocybin for Treatment-Resistant Depression Patients with treatment-resistant depression | 2018 | Clinical trial | n = 20 |
| Safety, Tolerability, and Efficacy of Psilocybin in 9 Patients With Obsessive-Compulsive Disorder Subjects with obsessive-compulsive disorder (OCD) | 2006 | Controlled clinical trial |