Single-dose psilocybin for treatment-resistant obsessive-compulsive disorder: A case report

This pre-print case study (2022) explores the effects of single-dose psilocybin (19.4mg) in an individual with OCD. Treatment led to improvements in OCD symptoms and positive changes to the individuals’ emotions, social and work function, and quality of life.


“Classic psychedelics, such as psilocybin, act on the brain’s serotonin system and produce striking psychological effects. Early work in the 1950s and 1960s and more recent controlled studies suggest benefits from psychedelic treatment in a number of conditions. A few case reports in recreational users and a single experimental study suggest benefit in patients with obsessive-compulsive disorder (OCD). Still, careful clinical data and long-term follow-up have been lacking. Here we describe a case of a patient with refractory OCD treated with psilocybin and followed prospectively for a year, with marked symptomatic improvement. We provide qualitative and quantitative detail of his experience during and after treatment. Improvement in OCD symptoms (YBOCS declined from 24 to 0-2) was accompanied by broader changes in his relationship to his emotions, social and work function, and quality of life. This individual was an early participant in an ongoing controlled study of psilocybin in the treatment of OCD (NCT03356483). These results are preliminary but promising, motivating ongoing investigations of the therapeutic potential of appropriately monitored and supported psychedelic treatment in the treatment of patients with obsessions and compulsions.”

Authors: Benjamin Kelmendi, Stephen A. Kichuk, Giuliana DePalmer, Gayle Maloney, Terrence H. Ching, Alexander Belser & Christopher Pittenger

Summary of Single-dose psilocybin for TR-OCD

Research on the use of psilocybin in the treatment of OCD is limited, but some case reports have indicated benefits. Anecdotes from individuals who have self-medicated with psilocybin to address their OCD symptoms continue to appear in various discussion forums.

The authors have begun a double-blinded, randomized, placebo-controlled trial of single-dose psilocybin in treatment-resistant OCD. An early participant experienced rapid and lasting improvement, but this response is not typical.

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PDF of Single-dose psilocybin for TR-OCD

Study details

Compounds studied

Topics studied
Obsessive-Compulsive Disorder

Study characteristics
Placebo-Controlled Double-Blind Case Study

1 Humans


Authors associated with this publication with profiles on Blossom

Benjamin Kelmendi
Benjamin Kelmendi is a board-certified psychiatrist and is an Assistant Professor in the Department of Psychiatry at the Yale University School of Medicine and is also a co-founder of the Yale Psychedelic Science Group.


Institutes associated with this publication

Yale University
The Yale Psychedelic Science Group was established in 2016.

Compound Details

The psychedelics given at which dose and how many times

Psilocybin 19.4 mg | 1x

Linked Clinical Trial

Efficacy of Psilocybin in OCD: a Double-Blind, Placebo-Controlled Study
This study aims to investigate the effects of oral psilocybin on OCD symptomatology and provide the first evidence of the neural mechanism that may mediate psilocybin's purported therapeutic effects on OCD.

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