Monoamine oxidase inhibitors (MAOIs) block the enzymes that break down serotonin and related compounds. Some are prescription antidepressants, and the beta-carbolines in ayahuasca are highly active reversible MAO inhibitors (McKenna et al., 198490003-5)). A 2024 review says the MAOIs in ayahuasca prevent the breakdown of tyramine, and that dangerously high tyramine can cause a hypertensive crisis (White et al., 2024).
A 2026 review of 219 publications plus user reports listed suspected serotonin toxicity when MAOIs were combined with substances such as amphetamine, dextromethorphan and MDMA, and fatalities that included combinations with 5-MeO-DMT (Rached et al., 2026). For psilocybin the record is one case report: a hypertensive emergency in a person who combined mushrooms, an amphetamine product and the MAOI tranylcypromine (Barnett et al., 2025).
The food side has been revisited: a 2018 review argues earlier tyramine warnings were overstated but says care is still needed because sensitivity varies (Gillman, 2018). This is a description of risk, not medical advice.
General information, not medical advice. In an emergency in Canada, call 911. For a mental-health crisis, call or text 9-8-8.
Sources
- McKenna, Towers and Abbott (1984), Monoamine oxidase inhibitors in South American hallucinogenic plants
- White et al. (2024), Ayahuasca and DMT adverse events and toxicity analysis
- Rached et al. (2026), Safety and efficacy of MAOIs in patients who use psychoactive substances
- Barnett et al. (2025), Hypertensive emergency case report
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