Ayahuasca

In people, the controlled evidence is one small trial. Among 29 adults with treatment-resistant depression, a single dose of ayahuasca lowered depression scores more than a placebo drink over 7 days, and 64% responded versus 27% on placebo [1]. An earlier open-label study in 6 inpatients found similar short-term drops [2]. No trial has followed people for months, and blinding is hard when one drink causes visions.

A network meta-analysis that adjusted for weak blinding found that only high-dose psilocybin, not ayahuasca, still beat placebo by the standard set in antidepressant trials [3]. Most of what is known about everyday use comes from surveys. Of more than 10,000 drinkers, 70% reported acute physical effects such as vomiting, 2.3% needed medical care afterwards, and 56% reported mental health effects in the following weeks, which most saw as part of a process of growth [4].

Psychotic episodes after ayahuasca are rare in published reports, and many of the people described had a personal or family history of psychosis [5]. Ayahuasca is not an approved medicine for any condition, and no study has tested the athletic, creative or longevity benefits that users credit it with.

• DMT, the active ingredient, is a Schedule I drug under US federal law. A few churches have legal permission to use ayahuasca in ceremonies, and laws differ by country.
• The vine in the brew is an MAO inhibitor. Combined with antidepressants such as SSRIs, some other drugs or certain supplements, it can cause dangerous serotonin toxicity.
• People with a personal or family history of psychosis, schizophrenia or bipolar disorder should not take it.
• Vomiting, diarrhea, a racing heart and higher blood pressure are common during a session, so people with heart disease should avoid it.
• In a large survey, more than half of drinkers reported mental health effects in the weeks after, and about 12% sought professional help. Unsupervised settings carried more risk of physical harm.