What is ayahuasca? The Amazonian brew, its contested history, and what science knows

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Ayahuasca is often described in a single breath as ancient, sacred and healing. Each of those words hides a debate. This guide explains what ayahuasca is, what archaeology and anthropology actually say about its age, how its chemistry works in general terms, what controlled research has and has not shown, and why it carries interaction risks that DMT on its own does not. For a side-by-side table of ayahuasca and DMT (timing, body effects, purging), see ayahuasca vs DMT.

What is ayahuasca?

Ayahuasca is a brew from the Amazon basin that combines DMT (N,N-dimethyltryptamine) with β-carboline alkaloids, chiefly harmine, harmaline and tetrahydroharmine (McKenna, Towers and Abbott, 1984; Riba et al., 2003). The International Narcotics Control Board describes it as a preparation made from plants indigenous to the Amazon basin, containing a number of psychoactive alkaloids, including DMT (INCB, 2010). We do not name the plants or describe how the brew is made. Evidence: established.

It has many names. Among the Shipibo-Konibo of the Peruvian Ucayali it is ayawaska or oni, and other Indigenous nations call it yage, caapi or camaranti, among other names (Favaron, Williams and Bédard, 2026). In the United States, the União do Vegetal church calls its sacramental tea hoasca (Gonzales v. O Centro Espírita, 2006). Evidence: established.

Who uses it has changed. The anthropologist Bernd Brabec de Mori describes three large, overlapping groups today: Indigenous and Mestizo people within their own communities; “neo-shamanic” and recreational users all over the world; and patients in modern medical and psychiatric research (Brabec de Mori, 2021). Each group understands what ayahuasca is, and what it does, in a different way. Evidence: established as a description; the framing is the author’s.

How old is ayahuasca? What the evidence says

You will often read that ayahuasca has been drunk for thousands of years. The evidence is less certain than that. Archaeology shows that psychoactive plants containing DMT-type compounds have been used in South American ritual for a very long time. What it has not yet shown is ancient drinking of ayahuasca itself. Evidence: unresolved for the age of the drinking practice.

The strongest find is a ritual bundle from a rock shelter in the Lípez Altiplano of southwestern Bolivia, radiocarbon dated to approximately 1,000 CE. Mass spectrometry of residues found traces of bufotenine, DMT, harmine and cocaine, suggesting at least three plants were part of the kit. The authors note it is a documented case of a bundle containing both harmine and DMT, “the two primary ingredients of ayahuasca” (Miller et al., 2019). The bundle was a snuffing kit, so it is evidence that both compounds were carried and used together in ritual, not proof that anyone drank a brew. Evidence: established for the residues; how they were used is unresolved.

Older still, a 2025 study of Chavín de Huántar in the Peruvian Andes, a ceremonial centre of roughly 1200 to 400 BCE, analysed bone tubes sealed in an underground gallery. Microbotanical and chemical analyses gave direct evidence of psychoactive plants in tubes used as inhalers, including the northernmost direct evidence of vilca and tobacco use in the pre-Hispanic Andes (Rick et al., 2025). Again, this is snuff, not a drink. For more on these finds, see ancient DMT snuffs and archaeology. Evidence: established for the residues.

On the drinking practice itself, anthropologists disagree. Brabec de Mori argues that many writers repeat “un-referenced and never tested assumptions” that Indigenous people used ayahuasca for healing over millennia. In his reading of the ethnography, Indigenous and Mestizo people historically used it mainly for divination, counter-witchcraft, warfare and communal ritual (Brabec de Mori, 2021).

He argues that the idea of ayahuasca as a cure probably dates to the rubber boom and its violent exploitation of Indigenous people, and that its framing as “healing” was built in the second half of the 20th century. He adds that the words “ceremony” and “shaman” came into use in the 1990s for sessions involving visitors (Brabec de Mori, 2021). This is one scholar’s argument from circumstantial evidence; other researchers write of centuries of use (Haupt et al., 2026). Evidence: unresolved.

How does ayahuasca work? The MAO mechanism in general terms

The key is an enzyme, monoamine oxidase (MAO). On its own, swallowed DMT does nothing noticeable. In a study of six experienced users, DMT taken by mouth produced no psychotropic effects and no DMT was recovered in urine; 97% of the recovered compounds were the MAO breakdown product, indole-3-acetic acid (Riba et al., 2015). The enzyme destroys it first. For more on that enzyme, see why DMT breaks down so fast. Evidence: established.

Ayahuasca’s β-carbolines are reversible MAO inhibitors. A 1984 laboratory study found ayahuasca samples were “extremely effective” inhibitors of MAO in vitro, that inhibition rose with the concentration of β-carbolines, and that their effects in combination were additive. At the time, the authors noted that this mechanism had been proposed to explain the brew’s oral activity but had not been experimentally confirmed (McKenna, Towers and Abbott, 1984). Evidence: established for the laboratory finding.

Later human work filled the gap: in a double-blind, placebo-controlled study of 18 volunteers, harmine was barely detectable in blood, which suggested it acts mainly in the gut and liver, where blocking MAO “would suffice to prevent first-pass metabolism of DMT” and let it reach the brain (Riba et al., 2003). Evidence: established in outline; the exact role of each alkaloid is less certain.

Two consequences follow. First, ayahuasca acts far more slowly and for longer than injected DMT; our ayahuasca vs DMT comparison sets out the timing. Second, because MAO also breaks down other substances, an MAO-inhibiting brew changes how the body handles some foods and medicines, which is the root of its main interaction risks below. For why DMT is cleared so quickly in the first place, see what is DMT.

Medicine, sacrament or something else?

In Indigenous use, Brabec de Mori writes, ayahuasca is understood mainly as an amplifying power for dealing with non-human beings in the animal, plant or spirit realms; its efficacy is not thought to depend on the drug but on correct communication between the healer, or sorcerer, and those powers. Modern medicine, by contrast, treats MAO inhibition and DMT activity as triggers for psychological and bodily responses. He argues the two views are so different that neither can be used to confirm the other (Brabec de Mori, 2021).

Writing from 15 years of fieldwork among the Shipibo-Konibo, Favaron and colleagues similarly argue that Indigenous use cannot be separated from its linguistic, cosmological and spiritual framework, and warn against reducing it to psychological projection (Favaron, Williams and Bédard, 2026). Evidence: these are interpretations, attributed to their authors, not settled findings.

In the 20th century, ayahuasca became the sacrament of Brazilian syncretic churches that have since expanded to urban Brazil, Europe and North America; members typically take part in ceremonies at least twice a month (Bouso et al., 2012). Their history and legal battles are covered in Santo Daime and UDV: the ayahuasca churches. Evidence: established.

Where does the name “Mother Ayahuasca” fit? Brabec de Mori notes that neo-animist renderings of “mother ayahuasca”, and of “teacher” or “master” plants, are very popular among Westerners, and that in the ceremonies he observed in Central Europe the substance itself was often worshipped as “mother”, “teacher” or “master” (Brabec de Mori, 2021). The figure also turns up in DMT reports: in 3,778 coded online accounts, “Gaia, Mother Ayahuasca, or Mother Nature” made up 34 of 1,719 entity encounters, or 2.0% (Lawrence et al., 2022). Evidence: established that the term is widely used; what, if anything, it refers to is a question of belief, not research.

What has research found, and what are its limits?

The research base is small and young. A 2026 scoping review found 26 registered interventional trials of DMT, ayahuasca or DMT combined with harmine on ClinicalTrials.gov. Most were phase I, mostly in medically and psychiatrically healthy adults, and primary outcomes were mostly about acute safety rather than treating a disorder (Stojanović et al., 2026). For trials of DMT itself, see DMT therapy research. Evidence: established for the count.

The depression trial is the best-known controlled study; its authors call it the first controlled trial of a psychedelic in treatment-resistant depression. Ayahuasca significantly lowered clinician-rated depression scores compared with placebo at one, two and seven days; at day 7, 64% responded on ayahuasca against 27% on placebo, and remission (36% against 7%) fell just short of significance (Palhano-Fontes et al., 2019). It is one small trial with a short follow-up, and vomiting is common enough to make blinding hard. Evidence: preliminary.

Observational studies of retreat-goers report improvements at the group level, but the 2026 review’s authors stress small samples, missing control groups and non-randomized designs, and note that some participants had persisting psychiatric complications linked to their use (Haupt et al., 2026). None of this shows that ayahuasca is a treatment. Evidence: preliminary.

What are the serious risks and interactions?

How often these interactions happen is less clear than the mechanism. The 2024 review, covering 78 articles, describes serotonin syndrome with ayahuasca as a theoretical concern, reported only in extremely rare case studies with no confirmed case found; it also concludes that serious adverse effects are rarely reported in healthy people in controlled settings (White et al., 2024). Evidence: preliminary for how often harm occurs.

A 2013 review of reports linking ayahuasca to life-threatening reactions found that some lacked accurate forensic or toxicology information and others did not involve traditional ayahuasca. Even so, it concluded the cases suggest that heart disease, liver disease and current use of serotonergic drugs or medications are contraindications (dos Santos, 2013). Evidence: established for the mechanism; preliminary for how often harm occurs.

Adverse effects short of emergencies are common. In the Global Ayahuasca Survey, 55.9% reported adverse mental health effects in the weeks or months afterwards, although about 88% of them saw these as part of a positive process, and about 12% sought professional support. Physical adverse effects were associated with having a physical health condition and with use in a non-supervised context, among other factors (Bouso et al., 2022). Those are associations in a self-selected online sample. Evidence: preliminary.

Animal studies at high amounts have shown harm to pregnancy and fetal development (White et al., 2024). Evidence: preliminary. Our safety page covers general psychedelic risks, and magic mushrooms and antidepressants explains serotonin interactions more broadly.

Is ayahuasca legal?

In Canada, the brew has no separate entry in the Controlled Drugs and Substances Act, but N,N-dimethyltryptamine is item 7 of Schedule III and harmaline is item 9, so a preparation containing them is controlled (consolidation current to 30 September 2026) (Justice Laws, CDSA). This is general information, not legal advice. A 2024 report by the Information Commissioner of Canada describes an application to Health Canada for a religious exemption to serve ayahuasca under section 56 of the Act (Information Commissioner, 2024). The details are in is DMT legal in Canada. Evidence: established.

Internationally, the picture is ambiguous. DMT is controlled under the 1971 UN Convention on Psychotropic Substances, but the International Narcotics Control Board said in its 2010 report that no plants are controlled under that convention and that preparations made from them, such as decoctions for oral use, are also not under international control, naming ayahuasca as an example (INCB, 2010). The US Supreme Court, by contrast, said in 2006 that it did not agree with a lower court that the convention does not cover hoasca, while still ruling for the church at that preliminary stage (Gonzales v. O Centro Espírita, 2006). Evidence: established for what each document says.

What we still don’t know

• How old the drinking of ayahuasca is. Ancient residues come from snuff kits and inhalers, not drinking vessels (unresolved).
• Whether ayahuasca has any lasting effect on depression. The randomized trial described here had 29 people and one week of follow-up (preliminary).
• Who is at risk of lasting psychiatric harm, since retreat studies lack control groups (preliminary).
• How common serious drug interactions are. The pharmacology is clear; confirmed cases are scarce and death reports often lack toxicology (unresolved).
• How each alkaloid contributes, given that brews vary (unresolved).
• How far research findings, made in screened volunteers, apply to the wider world of ceremonies and retreats (unresolved).

The fair summary: ayahuasca is a chemical combination with a real but debated history, a small and early evidence base, and specific risks that come from the very mechanism that makes it work. For the molecule at its centre, read what is DMT.

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