A large group of Brazilian scientists carried out the first randomized placebo-controlled trial with ayahuasca in 29 patients with treatment-resistant depression, and the results are encouraging.

Ayahuasca is a brew traditionally used for healing and spiritual purposes by indigenous populations of the Amazon rainforest. According to a new clinical trial published today in Psychological Medicine, ayahuasca is safe and alleviates symptoms of depression in patients who did not respond to conventional treatments; this time, compared to placebo. “This is the first controlled study with ayahuasca for depression, and the results are promising and interesting,” said Dráulio Araújo, professor of the Brain Institute at the Federal University of Rio Grande do Norte, who coordinated the trial.

The World Health Organization estimates that more than 300 million people suffer from depression, and about one-third do not respond to currently available antidepressants. In addition, most people won’t start experiencing the benefits of these medications until 2 weeks after they begin taking it.

A promising new rapid antidepressant effect can come from psychedelics. A recent uncontrolled study suggested a fast-onset antidepressant effect in a single session of ayahuasca1 in 17 patients with hard-to-treat depression. “We are very excited with these results. The effects were similar to the ones we observed previously. They had already improved in the first hours after ayahuasca intake,” said Jaime Hallak, a professor of psychiatry from the University of São Paulo, and a co-author of the study.

Although promising, these studies have not controlled for the placebo effect, which can be found in remarkably high numbers in clinical trials for depression, reaching 30-40% of the patients. In this new study, a large group of Brazilian scientists carried out the first randomized placebo-controlled trial with ayahuasca, treating 29 patients with treatment-resistant depression. Half of the patients were treated with ayahuasca, and the other half with placebo. “We observed a significant placebo effect, but the effects of ayahuasca were superior, and lasted longer,” said João Paulo Maia, a psychiatrist from the Onofre Lopes University Hospital, and co-author of this study. Significant improvements were already observed one day after the dosing session. “Seven days after the session the effect increased, and 64% of the patients responded to ayahuasca, while 27% responded to the placebo,” said Fernanda Palhano-Fontes, first author of the study.

Ayahuasca began to be used in religious settings in small urban Brazilian centers in the 1930s, reaching large cities in the 1980s, and expanding since then to several other parts of the world. “There is another psychedelic wave on its way, and we have a chance to make up for lost time. These are powerful substances that should be treated with great respect, and used in appropriate settings and with appropriate intentions,” concluded Dr. Araújo.

Rapid antidepressant effects of the psychedelic ayahuasca in treatment-resistant depression: A randomized placebo-controlled trial. Freely available at: https://doi.org/10.1017/S0033291718001356

The study was funded by the Brazilian National Council for Scientific and Technological Development (CNPq, grants #466760/2014 & #479466/2013), and the CAPES Foundation within the Ministry of Education (grants #1677/2012 & #1577/2013).


  1. Sanches et al. (2016). Antidepressant effects of a single dose of ayahuasca in patients with recurrent depression: A SPECT study. Journal of Clinical Psychopharmacology, 36(1), 77–81.

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