Single Dose of Psilocybin Quickly Alleviates Depression

A randomized clinical trial in Sweden enrolled 35 adults with moderate to severe recurrent major depressive disorder. Each participant received either a 25‑mg oral dose of psilocybin or a 100‑mg niacin capsule that produced flushing, so the study was double‑blind and used active placebo. Both groups also attended five psychotherapeutic support sessions over 17 days, including a preparation and a dosing session, to standardise the therapeutic context.

Rapid Symptom Relief

The psilocybin group showed a faster reduction in symptoms than the niacin group. On a self‑report version of the Montgomery‑Åsberg Depression Rating Scale, the difference appeared by the second day and continued for more than three months. On the clinician‑rated scale, depressive symptoms fell about seven points more in the psilocybin group by day eight, the study’s primary outcome, and the group stayed ahead through day 42. By day 42, remission rates were 53 % for psilocybin and 6 % for niacin.

After one year the advantage on the clinician‑rated measure had disappeared, with remission rates of 53 % for psilocybin and 41 % for niacin—a difference that could reflect chance. Psilocybin was generally well tolerated; most side effects were temporary headache, anxiety and hallucinations, but two participants experienced severe anxiety that lasted weeks and required medical attention. Blinding largely failed, with 94 % of the psilocybin group correctly guessing their treatment and most clinicians doing the same.

The study’s small size and the loss of blinding limit the strength of its conclusions. The authors note that the trial was not designed to provide firm evidence on long‑term effects, and that recruitment via social media may have attracted participants with high expectations. The results suggest that a single psilocybin dose can produce rapid and relatively lasting relief from depression, but further research with larger samples and better blinding is needed to confirm the durability of these benefits.