Why You Vomit on Ayahuasca

After my first ayahuasca ceremony, in which I felt almost nothing, I listened enviously to a man who vomited while envisioning Donald Trump. The president represented everything vile to him, he said. The retreat’s facilitator explained that people on ayahuasca (a tea made from a hallucinogenic Amazonian plant and consumed in shamanic ceremonies) often feel they’re expelling the vileness within themselves when they throw up. Then, before my very first ayahuasca vomit during my third ceremony, rotten fish appeared on the insides of my eyelids, and the word “vile” also came to mind. Afterward, the fish vision faded. Many describe similar experiences. “I was feeling ill in my stomach and was talking to an outer force, almost like a guide,” says Kristy Belich, a 31-year-old standup comedian in the Washington, DC, area. “They told me, ‘It is time.’ I had a little bucket next to me, and they told me to vomit until the green light stopped. The third time, the vomit light was orange and yellow.”

Nick Polizzi, a 39-year-old in Boulder, CO and author of The Sacred Science: An Ancient Healing Path for the Modern World, also remembers a profound ayahuasca vomit. “A pressure was building inside my body, encapsulating all of the suffering and torment, rising through my esophagus like mercury in a thermometer,” he recalls. “My eyes snapped open and out of my mouth came a sound that I did not know I was capable of making. It was a demonic groan, straight out of a horror movie. I fumbled around in the dark for my bucket and found it right as an even louder roar escaped my throat, accompanied by a few pints of vomit. In that moment, all the disorientation and fear stopped.”

Perhaps the most well-known effect of ayahuasca is its purgative effect—hence the bucket next to each participant’s mat. According to traditional belief, purging can occur through a number of means also including diarrhea, shaking, crying, and sweating, says Evgenia Fotiou, assistant professor of anthropology at Kent State University, who has interviewed shamans and ayahuasca ceremony participants around the world. People sometimes describe mental aspects of the trip bringing on the vomiting, and afterward, the journey often changes course, says Luís Fernando Tófoli, professor of medical psychology and psychiatry at the University of Campinas, who also studies ayahuasca.

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These effects stem from ayahuasca’s impact on the serotonergic system—involving the neurotransmitter serotonin—which influences many things, including mood and visual and auditory perception, says James Giordano, professor of neurology and biochemistry at Georgetown University Medical Center. The vomiting in particular comes from its action on the area postrema, the part of the brainstem that controls that urge to throw up. In this brain region, ayahuasca acts on 5HT3 serotonin receptors—which are also in the gut—potentially contributing to nausea, vomiting, and diarrhea, Tófoli tells me. Compounding the effects, ayahuasca increases serotonin levels in both the gut and the brain.

“The foul taste of the ayahuasca brew also accounts for nausea, but mostly soon after ingestion,” Tófoli says. “Since purging may take place a long time after that, this effect is probably not as important as the direct effect in the gut.” The liquid in the preparation also seems to contribute to the vomiting, he adds. Throwing up is less common after consuming ayahuasca in freeze-dried form.

Because ayahuasca’s impact on the area postrema is so strong, the vomiting is often more violent than usual pukes. “The nature of that kind of vomiting is exceedingly purgative,” Giordano tells me. “It’s a really deep, neurologically induced deep vomit. You literally feel as if you have vomited everything you’ve eaten since birth. It’s like this mega-hurl.”

The sheer strength of the vomiting partially explains why it can feel like you’re throwing up thoughts, emotions, or experiences, he adds. On top of that, people simply feel happier when they’re not sick, leading to the perception that negative feelings have left the body. There’s no known neurological reason why the vomiting feels more than physical, my experts posit; it just seems that way because of the emotional journey simultaneously taking place.

“There is probably a considerable influence of the social context,” Tófoli says. “In all ayahuasca traditions from South America that I know of, purging is considered as a sort of physical and spiritual cleansing, and it is not understood as an undesirable side effect.”

Many still believe that the cause of the vomiting is emotional, even if there's no science behind that reasoning. “I was told [by a shaman] that it is not the ayahuasca that makes one nauseous and sick during ceremony; it is the negative things that exist in the body, such as anger, depression, sadness, and fear, which are resisting leaving the body,” Fotiou says. “This was echoed in the way people discussed someone who had a bad time in a ceremony. They would attribute it to the fact that he or she had many negative things to purge…It was generally thought that once the purging was over, ayahuasca would take that person to an ecstatic state."

In fact, in cultures with rituals around ayahuasca, physical and mental purging are often not even viewed as separate phenomena. “You won’t find that separation between body and emotion in native cultures,” Fotiou says. “The body is where emotion and even knowledge lives.”

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