Ayahuasca and Amazonian Plants: Traditional Use, Botany and Safety

Safety first. Ayahuasca contains plant compounds that act as monoamine oxidase inhibitors (MAOIs). Reports describe severe, life-threatening serotonin syndrome when it was combined with other serotonin-affecting substances, including common over-the-counter products. [1] Anyone who has taken ayahuasca and then feels very unwell should get emergency care (911 in the US). Do not stop or change prescribed medicines on your own; talk with the prescriber: talking with a health professional.

What ayahuasca is

Ayahuasca is a plant brew traditionally used for therapeutic and ritual purposes by Indigenous groups of northwestern Amazonian countries such as Brazil, Peru, Colombia and Ecuador. It is made from two kinds of plants: one rich in dimethyltryptamine (DMT), usually the leaves of the Psychotria viridis bush, and one that supplies β-carboline compounds such as harmine, from the stalks of the Banisteriopsis caapi vine. [2] Another DMT-containing plant, Diplopterys cabrerana, is also named in medical literature. [1] This page does not describe how it is made or taken.

Botanical alkaloids

• DMT. A classic psychedelic that acts mainly on serotonin 5-HT2A receptors. [3]
• β-carbolines (harmine and relatives). B. caapi contains harmine, harmaline and tetrahydroharmine and has monoamine oxidase inhibitory activity, shown in laboratory and animal studies. [4] This enzyme-blocking effect is the reason for the interaction risk above.

Traditional history and context

A historical review notes that ayahuasca originates from the Amazon rainforest, that interest has risen strongly since the turn of the millennium, and that accounts range from evangelical praise to "horror stories" of physical and psychological harm. [5] Traditional use belongs to specific peoples and lineages of healers; this site does not reproduce ceremonies. See Indigenous traditions, ethics and conservation for concerns about outside demand.

What research shows

Evidence labels: promising but limited, insufficient evidence.

• Treatment-resistant depression: promising but limited. In a small randomized, double-blind, placebo-controlled trial of 29 patients, a single ayahuasca dose reduced depression scores more than placebo at one, two and seven days. At day seven, 64% responded versus 27% with placebo. [6]
• Overall picture. A 2024 review says studies suggest a good safety and tolerability profile, but there are few controlled studies, with small samples, single doses and short follow-up. [2]
• Other conditions: insufficient evidence. The same review mentions interest in post-traumatic stress and substance use disorders without established benefit. [2]
• Brain effects. Imaging studies of ayahuasca show disruption in the default mode network. [7]
• NIDA's summary. An analysis of 34 clinical studies of LSD, psilocybin or ayahuasca with 549 participants found no evidence of longer-term adverse effects, but poor outcomes may be more likely outside clinical use. [3]

Risks, interactions and who should be especially careful

• Serotonin syndrome and medicine interactions. The MAOI content predisposes users to serotonergic toxicity when combined with other serotonin-affecting agents. A 2026 case report describes a man who needed intubation and intensive care after ayahuasca followed by dextromethorphan and diphenhydramine; he recovered. [1] NIDA says serotonin toxicity is usually mild but can be life-threatening in rare cases. [3] See interactions by drug class and drug interactions and toxicology.
• Heart and blood pressure. A review of cardiovascular safety covers ayahuasca and says data are lacking for people with cardiovascular disease. [8]
• Mental health. Clinical trials exclude people with psychosis or bipolar disorder as a precaution. [3]
• Pregnancy. Effects of psychedelics in pregnancy are not well understood. [3] Ayahuasca-specific pregnancy data: not found.
• Setting. Most use occurs outside medical settings, where NIDA says dangerous behavior and injuries have been linked to these drugs. [3]

Quality and labeling

We did not find a regulator-published source on the content of ayahuasca products or retreat offerings, so claims about consistency or purity are a marketing claim unless tested.

Legal status

Not legal advice; laws change. The US federal Schedule I list names DMT; we did not find ayahuasca by name on that list. [9] How courts and regulators treat the brew in the US, Brazil, Peru and elsewhere: not verified here. See legal status by country.