Overall, acute physical health adverse effects were reported by 69.9% of the sample, with the most common effects being vomiting and nausea (68.2% of participants), headache (17.8%), and abdominal pain (12.8%). Only 2.3% of participants reported physical adverse events required medical attention for this issue. Among all participants, 55% also reported adverse mental health effects, including hearing or seeing things (28.5%), feeling disconnected or alone (21.0%), and having nightmares or disturbing thoughts (19.2%). However, of all respondents identifying these mental health effects, 87.6% believed they were completely or somewhat part of a positive growth process.

The researchers also identified several factors that predispose people to adverse physical events, including older age, having a physical health condition or substance use disorder, lifetime ayahuasca use, and taking ayahuasca in a non-supervised context.

The authors make the observation that ayahuasca has notable, although rarely severe, adverse effects according to the standards used for assessing prescription medicines. In that sense, they state that ayahuasca practices can hardly be assessed with the same parameters used for prescription medicines since the myriad of its effects includes challenging experiences that are intrinsic to the experience, some of which are considered as part of its healing process.

The authors add: “Many are turning to ayahuasca due to disenchantment with conventional Western mental health treatments, however, the disruptive power of this traditional medicine should not be underestimated, commonly resulting in mental health or emotional challenges during assimilation. While these are usually transitory and seen as part of a beneficial growth process, risks are greater for vulnerable individuals or when used in unsupportive contexts.”

Reference: “Adverse effects of ayahuasca: Results from the Global Ayahuasca Survey” by José Carlos Bouso, Óscar Andión, Jerome J. Sarris, Milan Scheidegger, Luís Fernando Tófoli, Emérita Sátiro Opaleye, Violeta Schubert and Daniel Perkins, 16 November 2022, PLOS Global Public Health.
DOI: 10.1371/journal.pgph.0000438