The Purge: Why Ayahuasca Makes You Vomit (and What It Means)

Most people who drink Ayahuasca vomit, and many also sweat, cry, shake, or pass loose stools. In Amazonian traditions this is "la purga", the purge, and it is understood not as a side effect but as the point: a cleansing of body, emotion, and spirit. Pharmacology tells a quieter story about why the body reacts this way. Both framings are worth understanding before you sit in a ceremony.

Why does Ayahuasca make you vomit?

The short answer: Ayahuasca is, chemically, an irritant to your gut. The brew combines a DMT-containing plant (usually Psychotria viridis) with the Banisteriopsis caapi vine, which is rich in β-carboline alkaloids, harmine, harmaline, and tetrahydroharmine. These β-carbolines are reversible inhibitors of the enzyme monoamine oxidase (MAO), which is the only reason orally-taken DMT becomes active at all. ^[1] If you want the underlying chemistry, our explainer on the difference between Ayahuasca, DMT and pharmahuasca covers it; the basics of the brew are in what Ayahuasca is.

But that same alkaloid load is hard on the digestive tract. Researchers developing injected and intranasal versions of DMT and harmine, specifically to avoid the stomach, describe the mechanism plainly: "circumventing the GI tract is assumed to spare intestinal 5-HT3 chemoreceptors on the terminals of vagal afferents, thus attenuating nausea, vomiting, and diarrhea." ^[2] In plainer terms, serotonin-sensitive receptors lining your gut detect the alkaloids and the surge of serotonin activity, fire a signal up the vagus nerve to the brain's vomiting centre, and your body responds. Bypass the stomach, and the nausea largely disappears.

There is a second, more mundane contributor: the brew itself. Traditional Ayahuasca is a thick, bitter decoction containing far more than DMT and harmine, including "emetogenic plant tannins", plant compounds that independently provoke vomiting. ^[2] So the purge is partly serotonergic and partly the simple fact that you have swallowed a strong, bitter plant medicine.

How common is the purge?

Common enough that ceremonies are designed around it, the bucket beside each mat is standard equipment. The largest dataset we have is the Global Ayahuasca Survey, which gathered self-reports from thousands of users. Among the 8,216 people analysed for physical effects, 69.9% reported an acute physical adverse effect, and vomiting combined with nausea was by far the most common, reported by 62.0% of participants. ^[3] Smaller observational studies have found rates ranging from almost universal to surprisingly low, depending on the brew and the individual. ^[4]

Crucially, the survey's authors flag the interpretive gap directly: in traditional ceremonies, "vomiting/nausea is not considered an adverse effect, but it is even sought out for its purging and perceived spiritual cleansing benefits." ^[3] When researchers count a purge as an "adverse event," they are applying a clinical-trial yardstick to an experience that the tradition treats as the medicine working. Reassuringly, in that same large survey only 2.3% of people reported needing any subsequent medical attention. ^[3] For a fuller picture of physical sensations, see what an Ayahuasca ceremony feels like.

"La purga": the traditional meaning of cleansing

In Amazonian practice, purga is not limited to vomiting. It includes diarrhoea, sweating, crying, yawning, trembling, and even laughing, any release the body offers up. The word for Ayahuasca itself in some traditions translates loosely as "the purge," and many healers consider the physical release inseparable from the psychological and spiritual one.

A 2024 qualitative study at the Takiwasi Center in Peru, where Ayahuasca is used within addiction treatment, interviewed eleven healers, plant specialists, and psychotherapists. They described purging as operating on three levels at once: a spiritual dimension tied to growth, an Amazonian framework of releasing harmful "energies" or loads thought to cause illness, and a clinical dimension with observable therapeutic benefit. The practitioners regarded it as "a critical part of healing." ^[5] This is traditional knowledge and clinical observation, not a proven biomedical mechanism, but it is consistent and central to how the medicine is used at the source.

Vomiting/nausea is not considered an adverse effect, but it is even sought out for its purging and perceived spiritual cleansing benefits.

This is also why the Ayahuasca dieta, the days of restricted, bland eating before a ceremony, matters. An emptier, simpler gut is thought to make the purge cleaner and less punishing.

What the purge actually involves: vomiting, diarrhoea, sweating

Expect variety, and expect it to be unpredictable from person to person and night to night:

• Vomiting is the most common and the most talked-about. It often arrives in waves rather than once, and many people report feeling lighter or clearer afterwards.
• Diarrhoea is less universal but well documented; both vomiting and diarrhoea are linked to raised serotonin activity in the gastrointestinal tract. ^[6]
• Sweating, shaking, and chills are frequent as the body's autonomic system responds.
• Emotional release, crying, and sometimes laughter, is counted as part of the purge in tradition, not separate from it.

Some people barely purge at all, even on a strong brew. That does not mean "nothing happened." There is no correlation worth relying on between how much you vomit and how meaningful the experience is.

The real risks: aspiration, dehydration, and the heart

Honesty matters more than reassurance here. The purge is usually self-limiting and harmless, but it is not risk-free, and the dangers are real enough that a properly run setting plans for them.

Aspiration. Vomiting while sedated, lying down, or deep in a non-ordinary state carries a genuine risk of inhaling stomach contents into the lungs. A pharmacology and toxicity review states it bluntly: "vomiting is considered dangerous, because it can theoretically lead to aspiration of gastric contents and thus endanger health and even life." ^[6] This is one practical reason facilitators monitor participants and why being left unattended is a red flag.

Dehydration and electrolyte loss. Repeated vomiting, diarrhoea, and heavy sweating across a long night can deplete fluids and salts. Reported serious harms after Ayahuasca disproportionately involve unsupervised settings, pre-existing illness, or dangerous drug interactions rather than the purge alone, but fluid loss is a recognised contributor and a reason rehydration and rest afterwards matter.

The cardiovascular load. Ayahuasca acutely raises heart rate and blood pressure, peaking within the first hour. ^[6] The strain of vomiting adds to that. For anyone with heart disease, high blood pressure, or related conditions this is a meaningful consideration, see Ayahuasca and your heart.

How this should shape your choices

If the purge is part of the experience, and for most people it will be, the variable you actually control is the setting. A credible centre screens participants for medical and psychiatric contraindications, keeps trained people awake and watching through the night, positions people so they can't aspirate, and has a real plan and route to emergency care. Those are exactly the things to ask about before you book; our questions to ask a retreat list and the pillar on choosing a retreat safely are built around this. The broader safety picture lives in our safety and contraindications pillar.

The purge is neither something to fear nor something to romanticise. It is a predictable physiological response that a long tradition has woven into a framework of meaning. Understanding both lets you walk in informed, knowing the bucket is normal, the release is usually benign, and the genuine risks are managed by where and with whom you sit, not by willpower.

If you are struggling with your mental health while reading this, please reach out to a qualified professional or, in the UK, the Samaritans on 116 123.