Wachuma vs ayahuasca: how the San Pedro cactus and the Amazonian brew compare

THE SHORT VERSION · SWIPE

▶ Watch it as a 20-second video

‹›

San Pedro and ayahuasca are often mentioned in the same breath, as if they were two flavours of one thing. They come from different plants, different landscapes and different chemical families. This guide compares them using peer-reviewed research, plant checklists and the text of Canadian law. For the basics of the brew, read what is ayahuasca; for peyote, see ayahuasca vs ibogaine vs peyote.

What plants are San Pedro and ayahuasca?

San Pedro is a columnar cactus. Kew’s World Checklist of Vascular Plants, the backbone of Plants of the World Online, accepts it as Echinopsis pachanoi and gives its native range as southern Ecuador to Peru; the same record notes it is naturalised in the Colombian Andes (Kew WCVP via ColPlantA). Other checklists disagree on the name: the WFO Plant List accepts Trichocereus macrogonus var. pachanoi, with Echinopsis pachanoi and Trichocereus pachanoi as synonyms (WFO Plant List). Older names in papers include cimora, another vernacular name recorded in northern Peru (Bussmann et al., 2007). Evidence: established; the classification itself is unresolved.

Wachuma (also written huachuma) is the Andean name used in archaeology for the same cactus (Rick et al., 2025; Uthaug et al., 2022). Ayahuasca is not one plant. It is a brew based on the vine Banisteriopsis caapi, which holds β-carbolines but little or no DMT; the DMT usually comes from the leaves of other plants, and some Amazonian groups use the vine alone (Egger et al., 2024). A controlled trial described the brew it studied as commonly obtained from B. caapi and Psychotria viridis (Riba et al., 2003). Our Banisteriopsis caapi guide covers the vine. Evidence: established.

Mescaline vs DMT: how do the active compounds differ?

Mescaline (3,4,5-trimethoxyphenethylamine) belongs to the phenethylamine family, the same broad family as many stimulants. A pharmacology review attributes its effects mainly to serotonin 5-HT2A to 2C receptors, and notes that, as a phenethylamine, it also produces sympathomimetic signs, the fight-or-flight effects on the body (Dinis-Oliveira et al., 2019). It is the main psychoactive compound of both San Pedro and peyote, and was first isolated from peyote in 1896 by the German chemist Arthur Heffter (Uthaug et al., 2022). Evidence: established.

DMT (N,N-dimethyltryptamine) is a tryptamine, the family of psilocin and serotonin itself. A 2024 review describes its effects as presumably due to agonism at 5-HT1A, 2A and 2C receptors, with other receptors possibly contributing; its reported affinity for sigma-1 receptors may be too weak to matter (Egger et al., 2024). Swallowed alone, DMT is nearly inactive because of first-pass metabolism; the β-carbolines in the vine inhibit MAO-A and let it through (Egger et al., 2024). On its own, DMT has a half-life of about 9 to 12 minutes (Halman et al., 2024). For the receptor story in depth, see DMT and the 5-HT2A receptor. Evidence: established for 5-HT2A; the role of other targets is preliminary.

So San Pedro is, chemically, a single-plant source of one main alkaloid, while ayahuasca depends on two chemical groups working together. Both end up at the same serotonin 2A receptor that classic psychedelics share, which is why researchers group them together despite the different molecules.

What do studies report about duration and effects?

There are no modern controlled trials of San Pedro itself; the cleanest timing data come from pure mescaline. In a randomized, double-blind crossover trial in 32 healthy people, mescaline had the longest effect duration of the three drugs tested (mean 11.1 hours, against 8.2 for LSD and 4.9 for psilocybin), because it took longer to reach peak levels. At equally strong doses, the trial found no qualitative difference in the altered states the three produced (Ley et al., 2023). Doses are not reproduced here. Evidence: established for these study conditions.

For ayahuasca, a double-blind, placebo-controlled trial in 18 experienced volunteers found subjective effects peaking between 1.5 and 2 hours, matching the time of highest DMT in the blood, with a significant rise in diastolic blood pressure at the higher dose (Riba et al., 2003). Our article on how long ayahuasca lasts covers the full time course. Evidence: established for these study conditions.

The main San Pedro data from people outside the lab are self-reports. In a web survey of 452 English-speaking adults who had used mescaline, most named peyote or San Pedro as the source of their most memorable experience, and the intensity of acute effects did not differ between mescaline types. Respondents rated mystical-type effects as moderate and challenging effects as very slight (Uthaug et al., 2022). The sample was self-selected, so these figures describe the respondents, not users in general. Evidence: preliminary.

What does the archaeological record show?

San Pedro at Chavín de Huántar

Chavín de Huántar, a monumental ceremonial centre in the Peruvian Andes dated to about 1200 to 400 BCE, is where San Pedro’s image is clearest. A 2025 study notes that the only psychoactive plant unequivocally depicted in Chavín’s iconography is the San Pedro cactus, carved on a granite plaque found in place in the Circular Plaza (Rick et al., 2025). Evidence: established for the image.

The same team then tested 23 artefacts, mostly bone tubes, from a sealed underground gallery. They found direct microbotanical and chemical evidence of vilca (Anadenanthera colubrina, a DMT-family snuff plant) and wild tobacco, not of San Pedro (Rick et al., 2025). The authors list San Pedro and ayahuasca among plants that have been suggested for Chavín ritual, but the physical residue they recovered points to snuff. Our article on ancient DMT snuffs covers vilca. Evidence: established for the residues; how San Pedro was used at Chavín is unresolved.

A continuing healing tradition in northern Peru

An ethnobotanical study of the plant markets of Trujillo and Chiclayo notes that traditional medicinal plant use in northern Peru dates back to the first millennium BC or at least to the Moche period (AD 100 to 800), and that the first detailed study of a hallucinogen in Peru focused on San Pedro, with cimora studied from the 1940s (Bussmann et al., 2007). A survey paper adds that Peru has passed legislation protecting traditional use of Indigenous plant medicines such as San Pedro (Uthaug et al., 2022). For ayahuasca’s own history, which historians still debate, see what is ayahuasca. Evidence: established for the studies; the exact age of each tradition is unresolved.

Is San Pedro endangered, like peyote?

No. Kew’s record shows Echinopsis pachanoi assessed as Least Concern on the IUCN Red List (Kew WCVP via ColPlantA). Peyote is a different case: it has been ranked Vulnerable on the IUCN Red List, and cactus ecologists studying wild Texas populations describe it as threatened by habitat loss and over-harvesting (Ermakova et al., 2020). One survey paper argues that decriminalisation measures that include peyote may add to pressure on wild plants (Uthaug et al., 2022). That is a reason the two mescaline cacti should not be treated as interchangeable in discussions of demand. Evidence: established for the listings; the size of any trade effect is unresolved.

What does research say about risks and interactions?

For ayahuasca, the largest dataset is the Global Ayahuasca Survey of 10,836 self-selected people. Acute physical effects, mainly vomiting, were reported by 69.9%, and 2.3% reported needing medical attention afterwards; 55.9% reported adverse mental health effects in the following weeks or months, and around 12% sought professional support (Bouso et al., 2022). Evidence: preliminary, from a self-selected survey.

Ayahuasca’s MAO inhibition is the main interaction concern. A 2026 case report describes a man who needed intubation and intensive care for severe serotonin syndrome after ayahuasca followed by an over-the-counter cough medicine containing dextromethorphan; the authors stress that the brew’s MAO inhibitors predispose users to serotonin toxicity with other serotonergic drugs (Pack et al., 2026). Our ayahuasca vs DMT guide covers this in more detail. Evidence: established mechanism; individual cases are case reports.

Mescaline’s profile in a review of reports is mostly of mild intoxications with sympathomimetic signs, and the authors note that most reports lacked any lab confirmation of what was taken (Dinis-Oliveira et al., 2019). A 2026 systematic review found raised blood pressure, headache, nausea and vomiting frequently reported, but only 10 of 66 eligible studies were suitable for analysis (Shaw et al., 2026). In the healthy-volunteer trial, mescaline caused slightly more adverse effects 12 to 24 hours later than LSD or psilocybin (Ley et al., 2023). Evidence: preliminary.

Interaction research for both is thin. A 2024 systematic review of drug interactions with classic psychedelics found 52 human studies, of which 4 involved mescaline, 3 DMT and only 1 ayahuasca (Halman et al., 2024). Evidence: established that the evidence base is small.

Are San Pedro and ayahuasca legal in Canada?

Schedule III of the Controlled Drugs and Substances Act lists DMT as item 7, harmaline as item 9 and harmalol as item 10, each with any salt; harmine is not named (Justice Laws, CDSA). Because DMT is scheduled, ayahuasca falls under the Act; our DMT and Canadian law guide covers the religious exemptions some churches have sought. Evidence: established.

Mescaline is Schedule III item 17, worded “Mescaline (3,4,5–trimethoxybenzeneethanamine) and any salt thereof, but not peyote (lophophora)”. The exclusion names peyote only; neither San Pedro nor any of its botanical names appears anywhere in the Act we read, which was current to 30 September 2026 (Justice Laws, CDSA). How the mescaline entry applies to a cactus that contains mescaline but is not peyote is a legal question this article does not answer. This is general information, not legal advice. Evidence: established for the wording.

What we still don’t know

• How San Pedro itself, rather than pure mescaline, behaves in controlled studies; none were found.
• How San Pedro was prepared or used at Chavín; the carved image is clear, the residue evidence is not.
• Which botanical name will settle; major checklists still disagree.
• Whether mescaline’s reported mental-health findings hold up in patients rather than survey respondents.
• How common serious interactions with ayahuasca are; the published record is mostly case reports.

For DMT’s chemistry and history, start with the pillar guide, what is DMT.

Shroomverse sells mushroom products. This article is general information about San Pedro and ayahuasca. It is not medical, legal or purchasing advice, and it does not recommend any product, ceremony or retreat.