Ayahuasca Vine (Banisteriopsis caapi)

Safety first. The vine contains compounds that block the enzyme monoamine oxidase (MAO). A 2026 case report describes severe serotonin syndrome with respiratory failure after ayahuasca was followed by over-the-counter dextromethorphan and diphenhydramine. [1] Anyone who feels very unwell after taking an ayahuasca preparation should get emergency care (911 in the US; Poison Help 1-800-222-1222). Do not stop or change prescribed medicines on your own: talking with a health professional. This page gives no preparation or use instructions and does not help identify the plant.

What it is

Banisteriopsis caapi is a liana (woody vine) of the Amazon basin in the Malpighiaceae family. GBIF lists it as an accepted species name. [2] [3] Its stems are the source of the harmala alkaloids harmine, harmaline and tetrahydroharmine. [4] "Ayahuasca vine" names the plant; "ayahuasca" usually names a brew, and the vine and brew are not the same thing. A 2024 review describes ayahuasca as a decoction of two plants, a DMT-rich bush and the vine, traditionally used for therapeutic and ritual purposes by Indigenous groups of northwestern Amazonian countries such as Brazil, Peru, Colombia and Ecuador. [5] See the ayahuasca guide.

Harmala alkaloids and MAO inhibition

Substance versus source matters here. The vine supplies harmala alkaloids (also called beta-carbolines); it does not supply DMT. DMT comes from other plants, such as Psychotria viridis or Diplopterys cabrerana. [1]

• In laboratory tests, harmine and harmaline strongly inhibited human MAO-A and MAO-B enzymes. [6]
• A 1984 study found beta-carbolines to be highly active, reversible MAO inhibitors, and found that ayahuasca samples inhibited MAO in the laboratory in proportion to their beta-carboline content. [7]
• In 10 healthy male volunteers, the amounts of each harmala alkaloid recovered in urine varied greatly (from 9 to 65%), so how the body handles them is not uniform. [8]

See harmala alkaloids and other compounds and DMT: compound guide.

Variability: why no figure applies to "the vine"

A Brazilian study analyzed 159 vine samples and 33 ayahuasca samples. It reported high variability between samples, higher harmine in native than cultivated vines, and differences between regions. The authors conclude this variability is a challenge for standardizing material used in research. [9] A laboratory comparison of stem material also found that commercial stems had lower amounts of several marker compounds and lower MAO-inhibiting and antioxidant potency than the more concentrated bark of a large branch. [6] We therefore give no typical content, strength or equivalence for the vine. One sample must not be used to judge another.

What research shows

Evidence labels used here: preclinical (cells or animals only), insufficient evidence, evidence of harm.

• Parkinson's disease: preclinical. In marmosets given a toxin that causes parkinsonism, vine extract mildly improved movement disability but did not increase the response to the standard drug L-DOPA or reduce dyskinesia. [4] An earlier review summarizes trials of vine and harmine-containing extracts in parkinsonism in the 1920s and 1930s and proposes reconsidering harmine; these were early reports, not modern controlled trials. [3] For people today: insufficient evidence.
• Depression, PTSD and addiction: the research concerns ayahuasca as a whole brew, with few, small, single-dose, short-follow-up controlled studies. [5] It cannot be assigned to the vine alone.
• Antidepressant effect of the vine alone in people: Proper evidence not found in our PubMed searches.

Risks, interactions and special groups

• Serotonin syndrome. See the case above. NIDA says serotonin toxicity is usually mild but can be life-threatening in rare cases. [10]
• Medicines. MAO inhibition can interact with many substances. No universal list exists; each combination needs checking with a pharmacist or prescriber. See interactions by drug class and drug interactions and toxicology.
• Vomiting and purging. A review of Amazonian traditions says emesis and purging are culturally meaningful and are among the main pharmacological effects of the brew. [11]
• Mental health, heart disease, pregnancy, children: Proper evidence not found specific to the vine alone. Clinical research on psychedelics excludes people with psychosis or bipolar disorder as a precaution. [10]

Cultural context

The same review notes that global popularity, including shamanic tourism, has led to a cultural distancing from traditional meanings. [11] Traditional use belongs to specific peoples and lineages. See Indigenous traditions, ethics and conservation. Conservation status of the vine: Proper evidence not found in the sources we read.

Legal status

Not legal advice; laws change. We searched the US federal lists in 21 CFR 1308.11 to 1308.15 and did not find Banisteriopsis caapi or harmine named; DMT is named in Schedule I. [12] Other countries and US states: not verified here. See legal status by country.