Ayahuasca Safety and Contraindications

Ayahuasca is not benign, and most of its serious dangers are predictable and preventable. The single most important thing to understand before considering a ceremony is that certain medications and health conditions turn a manageable experience into a potentially life-threatening one, which is why honest screening matters more than anything else. This is general education, not medical advice, and nothing here means anyone is safe to participate.

Why Ayahuasca carries real risk

Ayahuasca is a brew combining a plant containing the psychedelic compound DMT with a plant containing β-carboline alkaloids such as harmine, which act as monoamine oxidase inhibitors (MAOIs). ^[1] The MAOIs are what make oral DMT active at all, without them, the body would break it down before it reached the brain. ^[1] But that same MAOI activity is the root of most of Ayahuasca's dangerous interactions. An MAOI slows down enzymes that normally metabolise certain neurotransmitters and substances, so things that would ordinarily be cleared safely can instead accumulate to harmful levels.

This is not a reason to be frightened into silence. It is a reason to be thorough. The most serious harms recorded around Ayahuasca are overwhelmingly linked to drug interactions, undiagnosed or undisclosed health conditions, toxic additives in the brew, and inadequate screening, not to the traditional brew taken by a properly screened person in a competent setting. ^[2]

Medication interactions, explained conceptually

You do not need to be a pharmacologist to grasp why these interactions matter. The underlying logic is consistent: Ayahuasca changes how your body handles other substances, and it pushes serotonin and blood-pressure systems in the same direction as several common drugs.

• SSRIs and SNRIs (antidepressants). These increase serotonin signalling. Adding an MAOI on top can drive serotonin too high, which is the mechanism behind serotonin syndrome, agitation, rapid heart rate, high temperature, muscle rigidity, and in severe cases death. ^[3] Observational data from religious users on antidepressants has not shown frequent catastrophic outcomes, but the theoretical and case-report risk is serious enough that reputable centres screen for these drugs and treat the combination with great caution. ^[3]
• Other serotonergic substances. The same caution extends beyond prescription antidepressants, to certain migraine medications, some pain medications, supplements such as St John's Wort, and recreational stimulants like MDMA or amphetamines. Stimulants are especially dangerous with an MAOI on board, because the MAOI prevents their normal breakdown and can trigger a hypertensive crisis. ^[2]
• Lithium. Lithium deserves separate emphasis because the risk is not a gradual one. Co-use with psychedelics has been associated with seizures and grand-mal events in published case reports; the mechanism is not fully understood but appears to involve altered neuronal excitability. ^[4] This is among the clearest hard contraindications in the field.

The honest position is this: the only safe way to handle any prescribed medication is to discuss it with the clinician who prescribed it, well in advance. A responsible retreat will ask about every medication and may decline you, and being declined is the system working.

Cardiovascular risk

Ayahuasca acutely raises blood pressure and heart rate. Controlled human studies have measured transient, sympathomimetic increases, for example, a significant rise in diastolic blood pressure at higher doses, peaking roughly an hour to ninety minutes after drinking. ^[5] In a healthy person these changes are usually modest and temporary. ^[5]

For someone with uncontrolled hypertension, a heart condition, a history of stroke, or an arrhythmia, the same transient spike is a genuine hazard rather than a footnote, and it can be compounded by the physical stress of a long, intense night and repeated vomiting. Cardiovascular conditions are routinely listed as contraindications, and assessing them is part of why screening must include an honest medical history. ^[2]

Psychiatric contraindications

Ayahuasca is a powerful psychoactive experience, and for some people it can precipitate lasting harm rather than insight. The clearest concern is for people with a personal or family history of psychosis, schizophrenia, schizophreniform disorders, or bipolar disorder. Case reports describe Ayahuasca precipitating prolonged psychotic episodes and manic switches in vulnerable individuals, and researchers advise that people with these histories, or with current psychotic or manic symptoms, should avoid Ayahuasca and DMT. ^[6]

This is not about stigma; it is about a substance that profoundly alters perception interacting with conditions defined partly by altered perception. A history of anxiety or depression has also been associated with more difficult mental states afterward in survey data, which is another reason a thorough screening conversation, and ideally input from your own mental-health clinician, matters. ^[7]

Being turned away by a centre that screens carefully is not a failure of access. It is the safeguard doing exactly what it is supposed to do.

Physical safety risks during ceremony

Beyond pharmacology, the ceremony itself carries practical risks. Intense purging, vomiting and sometimes diarrhoea, is extremely common: in the largest survey to date, nearly 70% reported acute physical effects, predominantly vomiting, and around 2% reported needing subsequent medical attention. ^[7] In traditional Amazonian practice this purging is understood as part of the process rather than as harm, but it still carries downstream risks: dehydration, electrolyte disturbance, and, at the opposite extreme, dangerous over-drinking of water, which has been implicated in at least one death. ^[2]

Other physical risks are environmental: disorientation can lead to falls or injuries if the space is unsafe or unsupervised, and a person in an altered state needs attentive sitters nearby. ^[2]

Deaths are rare, and the record is sobering about why they happen. Reviews of deaths reported in the media found that no autopsy has attributed a death to acute intoxication from the traditional brew itself; the deaths instead trace to toxic additives (notably tobacco preparations and scopolamine-containing plants added by some operators), drug interactions, undisclosed health conditions, and the absence of basic safety standards. ^[2] Almost every one of these factors is addressable by competent screening and a responsible setting.

Psychological risks

The deepest risks are not always physical. An Ayahuasca experience can surface trauma without warning, and for some people the result is re-traumatisation or lasting distress rather than relief. Difficult experiences are common and are not inherently harmful, but the line between a hard-but-integratable night and genuine psychological injury depends heavily on preparation, the skill of the people holding the space, and support afterward. ^[7]

If you are in mental-health crisis, Ayahuasca is not a substitute for care, and an intense psychedelic experience can make an acute crisis worse. Anyone experiencing thoughts of self-harm or suicide should reach out to a crisis line or qualified clinician, in the US and Canada you can call or text 988, and in the UK you can call 111 or the Samaritans on 116 123.

What good screening looks like

Because nearly all of Ayahuasca's serious risks are predictable, the quality of a centre's screening is the single most useful safety signal available to a prospective participant. Rigorous screening is not a form to rush through, it is a real process. Good screening typically:

• Asks in detail about all medications and supplements, names the serotonergic and other interacting drugs specifically, and is prepared to decline or defer participation rather than work around a contraindication.
• Takes a genuine medical history, including cardiovascular conditions, seizure history, pregnancy, and other physical risks.
• Asks about personal and family psychiatric history, including psychosis, bipolar disorder, and schizophrenia, and treats those answers seriously.
• Is willing to say no. A centre that accepts everyone, downplays interactions, or tells you to stop your medication is showing you a red flag, not reassurance.
• Offers preparation and integration support, not just the ceremony itself.

No article and no centre can tell you that you personally are safe to participate. What screening can do is catch the predictable dangers before they become emergencies. If you are weighing a retreat, treat the rigour of its screening as a core part of the decision, our guide on choosing a retreat goes deeper into how to evaluate a centre's safety practices, and any health question that touches your own medications or conditions belongs with your prescriber and the centre, not with the internet.