Antidepressant Effects of a Single Dose of Ayahuasca in Patients With Recurrent Depression

Abstract

Ayahuasca is an Amazonian botanical hallucinogenic brew which contains dimethyltryptamine, a 5-HT2A receptor agonist, and harmine, a monoamine-oxidase A inhibitor. Our group recently reported that ayahuasca administration was associated with fast-acting antidepressive effects in 6 depressive patients. The objective of the present work was to assess the antidepressive potentials of ayahuasca in a bigger sample and to investigate its effects on regional cerebral blood flow. In an open-label trial conducted in an inpatient psychiatric unit, 17 patients with recurrent depression received an oral dose of ayahuasca (2.2 mL/kg) and were evaluated with the Hamilton Rating Scale for Depression, the Montgomery-Åsberg Depression Rating Scale, the Brief Psychiatric Rating Scale, the Young Mania Rating Scale, and the Clinician Administered Dissociative States Scale during acute ayahuasca effects and 1, 7, 14, and 21 days after drug intake. Blood perfusion was assessed eight hours after drug administration by means of single photon emission tomography. Ayahuasca administration was associated with increased psychoactivity (Clinician Administered Dissociative States Scale) and significant score decreases in depression-related scales (Hamilton Rating Scale for Depression, Montgomery-Åsberg Depression Rating Scale, Brief Psychiatric Rating Scale) from 80 minutes to day 21. Increased blood perfusion in the left nucleus accumbens, right insula and left subgenual area, brain regions implicated in the regulation of mood and emotions, were observed after ayahuasca intake. Ayahuasca was well tolerated. Vomiting was the only adverse effect recorded, being reported by 47% of the volunteers. Our results suggest that ayahuasca may have fast-acting and sustained antidepressive properties. These results should be replicated in randomized, double-blind, placebo-controlled trials.

In the evidence

This study is part of the evidence base for 2 syntheses in the library. Here is how each one recorded it.

• State of the evidence: Ayahuasca for depression ↑Supports

  A single oral dose of ayahuasca was associated with significant decreases in depression rating scale scores from 80 minutes to day 21, alongside increased blood perfusion in mood-regulating brain regions.

  Synthesized October 22, 2026

• State of the evidence: Ayahuasca ↑Supports

  A single oral ayahuasca dose was associated with significant decreases in depression rating scale scores from 80 minutes to day 21, alongside increased blood perfusion in mood-related brain regions.

  Synthesized October 19, 2026

Comparable studies

Other non-randomized and open-label trials on ayahuasca for depression, most cited first.