Abstract Ayahuasca is a psychedelic plant brew originating in the Amazon basin. It is typically made from two basic components: the ayahuasca vine (Banisteriopsis caapi), containing various harmala alkaloids, and the leaves of a plant containing the potent psychedelic dimethyltryptamine (DMT), such as the chacruna plant (Psychotria viridis). Evidence suggests the brew has been used for at least hundreds of years, primarily by indigenous tribes for a range of purposes including psychological and physical healing. The components of the brew exert a range of neurochemical effects, with recent research suggesting it may be effective in treating depression, anxiety, and addiction. The harmala alkaloids found in the vine are monoamine oxidase-A enzyme inhibitors (MAOIs). These compounds prevent the deamination of DMT as well as exerting their own psychotropic effects. DMT is known to modulate the signalling of serotonin and dopamine via serotonin and dopamine receptor agonism, as well as sigma-1 agonism. Interest in the plant brew has increased dramatically in recent years, with large numbers of ‘ayahuasca tourists’ visiting the Amazon basin to partake in ceremonies with the intention of treating a range of different conditions. Similarly, research into ayahuasca has increased, both in naturalistic and clinical settings, with potential medicalization giving rise to complex ethical issues that must be carefully considered.