San Pedro (Huachuma)

Archaeological and iconographic evidence

A Spanish-language review of archaeological and ethnographic evidence from northern Peru reports ritual use of the San Pedro cactus for magical-religious purposes in the Cupisnique (dated there to about 1500 BC), Chavin (about 1000 BC), Moche (AD 100 to 750) and Lambayeque (AD 750 to 1350) cultures. A separate study of plant use in northern Peru and southern Ecuador places the roots of traditional healing in the region in the Cupisnique culture early in the first millennium BC, so sources differ on the earliest dates.

An ethnobotanical survey of northern Peru reports that San Pedro (Echinopsis pachanoi) often appears in Cupisnique and Moche iconography and that its use can be traced to the Moche culture. A pharmacology review states that archaeological studies in the United States, Mexico and Peru suggest mescaline-containing cacti have been used for more than 6000 years, without separating San Pedro from peyote in that general statement.

Colonial suppression and continuity

The same pharmacology review reports that sixteenth-century Spanish chroniclers considered these cacti diabolic, which led to their prohibition, yet their use persisted and has spread over roughly the last 150 years. The ethnobotanical survey authors write that five hundred years of suppression by church, state institutions and Western medicine have not destroyed the tradition in northern Peru, and describe San Pedro as still central to the curing ceremonies of healers there.

Persistence among the Saraguro of southern Ecuador

A study based on ten interviews with recognized Saraguro healers (yachakkuna) in southern Ecuador, carried out in 2010 and 2011 with the Saraguro Healers Council, reports that the Saraguro maintained their healing traditions through the colonial period and that San Pedro is among the sacred and psychoactive plants they use. The authors present the healing system as an expression of Saraguro identity as an Andean people. Comparing the two regions, a further study reports that much original plant knowledge has already been lost in Ecuador, while northern Peru retains extensive knowledge.

Names for the cactus

Sources use several names. A pharmacology review uses wachuma for the South American cacti Trichocereus pachanoi, T. peruvianus and T. bridgesii. An ethnobotanical survey of northern Peru gives cimora as another vernacular name for San Pedro (Echinopsis pachanoi), and the Saraguro study reports the local names aguacolla and San Pedrillo. The spelling huachuma appears in a 2025 case study of a ceremony described as Huachuma (San Pedro cactus).

Genus names and the plant versus the practice

Authors place the plants in different genera. One chemical study describes the group as the subgenus Trichocereus of the genus Echinopsis, while others write Trichocereus pachanoi or Echinopsis pachanoi for the same species. This page follows each source's usage. In everyday speech the name San Pedro also covers the ceremony: the 2023 Dutch survey of ceremonial use refers to ceremonial San Pedro use, and the systematic review treats San Pedro and peyote as the two best-known mescaline-containing cacti.

Ritual vocabulary

In northern Peru the altar around which healing rites are performed is called a mesa, and the healer is described in the review literature as a master shaman or curandero. The Saraguro study uses mesas and mesadas for its magical-religious rituals, limpia for a cleansing rite and soplada for a rite involving blowing, and calls the healers yachakkuna. These are terms from the cited authors, and meanings vary between communities.

The mesa in northern Peru

The review of northern Peruvian evidence describes the contemporary mesa as a sophisticated ritual performed in the early hours of Tuesdays and Fridays, which are described as sacred days in Andean religions. Its stages are given as raising the mesa with tobacco and alcohol, ingesting San Pedro, locating the illnesses, cleansing the harm, and flourishing the sick person. The authors add that San Pedro is sometimes replaced by an infusion of other plants and seeds with hallucinogenic components.

An ethnobotanical survey reports that San Pedro, together with additives such as Brugmansia, Datura ferox and tobacco, remains central to the curing ceremonies of healers in northern Peru, and that guinea pigs are used there as diagnostic instruments. The sources reviewed describe the rite at overview level only and do not set out a procedure.

Saraguro mesas in southern Ecuador

In the Saraguro account, healers called rikuyhampiyachak use San Pedro during mesas and mesadas as a sacred drink to reach an ecstatic state and contact with the supernatural. The authors report that some people weep after drinking it, which healers regard as spiritual healing, and that vomiting or diarrhea is understood as removing agents that harm the patient. The study does not discuss safety or risk for this plant.

Contemporary ceremonial settings

Outside the Andes, ceremonial use has been studied in small samples. One survey followed 42 participants at ceremonial psychedelic retreats in the Netherlands, and an online survey of 452 mescaline users found that 66 percent had used San Pedro and 97 percent of respondents took mescaline orally. A 2025 case study followed one woman through separate ayahuasca and huachuma ceremonies using interviews, stool samples and symptom scales.

Traditional healing and divination

In northern Peru the mesa is described as a rite to treat enchantment and bad luck, locate illness and cleanse harm. The Saraguro study lists supernatural diseases such as shuka, described there as mal de ojo, together with anxiety, purgation, inflammation and wound disinfection among uses reported by healers. These are claims held within the traditions, expressed in their own categories of illness, and they are not clinical findings.

A broader survey of 510 medicinal plants in northern Peru found that the largest group, 207 species, was used for magical or ritual ailments. That count covers all plants surveyed and is not specific to San Pedro.

Reasons given by contemporary users

In the online survey of mescaline users, 74 percent reported being motivated to explore spirituality or connect with nature, and large majorities saw mescaline as relevant to personal growth, spiritual growth and psychotherapeutic work. Respondents reported many pre-existing mental health conditions and most of them reported improvement afterward. These are self-reports from a cross-sectional, self-selected sample, and the authors state that causality cannot be inferred.

Psychiatric uses described in the literature

A 2026 systematic review of mescaline in psychiatric contexts reports that included studies described improvements in depression scales, well-being, nicotine dependence, alcohol use and obsessions. Those studies mostly concerned mescaline or peyote rather than San Pedro, and the review describes the literature as limited and of highly variable quality.

Studies of the cactus itself

No randomized or otherwise controlled study of San Pedro cactus, or of a San Pedro ceremony, was found. A PubMed search for Trichocereus pachanoi, San Pedro cactus and Echinopsis pachanoi returned 20 records, which were mostly chemical, ethnobotanical or historical, and a separate search of mescaline titles returned human pharmacology trials of pure mescaline. A Consensus search could not be completed because of a usage limit. The observational and ethnographic work cited here describes practice and self-reported experience, and it cannot show what the cactus or the ceremony does.

Controlled studies of pure mescaline

A Swiss randomized, double-blind, placebo-controlled crossover study in 16 healthy adults tested several doses of mescaline and reported dose-dependent subjective effects, increases in blood pressure and heart rate, a plasma half-life of about 3.5 hours, and effects lasting from about 6.4 to 14 hours depending on dose. Co-administration of a 5-HT2A receptor blocker reduced the effects, which the authors take to indicate mediation mainly by that receptor.

A second randomized crossover study in 32 healthy participants compared mescaline, LSD and psilocybin at psychoactive-equivalent doses. It found no qualitative differences in the altered states produced, a longer mean duration for mescaline (11.1 hours), and slightly more subacute adverse effects with mescaline. Both studies used healthy volunteers and purified mescaline in a clinical setting, so their findings should not be carried over to cactus preparations, ceremonial settings or patients.

Surveys, a case study and a systematic review

The 2026 systematic review screened 2770 references, found 66 meeting inclusion criteria and judged only 10 suitable for analysis, concluding that conclusions on psychological and somatic effects were not possible. The Dutch survey of 42 ceremony participants described tentative results, with spiritual experiences strongly expressed and a complete mystical experience in about two thirds. The single-patient 2025 case study reported falls in depression scores after both ceremonies but is described by its authors as hypothesis generating.

Plant chemistry

An analysis of 14 taxa and cultivars of the subgenus Trichocereus found mescaline in all of them, ranging from 0.053 to 4.7 percent of dry weight, with the highest concentrations in E. pachanoi from Peru, which the authors link to documented shamanic use. Another study reported minor phenethylamines in San Pedro and peyote, including lophophine, lobivine and homopiperonylamine. Neither study tested effects in people.

Effects reported in controlled settings

A pooled analysis of two placebo-controlled studies (48 healthy participants, 96 administrations) reported that nausea was dose-limiting. Systolic blood pressure stayed below 180 mmHg, but diastolic pressure exceeded 100 mmHg after 6 percent of administrations, heart rate exceeded 100 beats per minute after 3 percent and body temperature exceeded 38 degrees Celsius after 5 percent. Kidney and liver function and blood counts stayed normal, and flashbacks were reported after 2 percent of administrations.

The Swiss crossover study also reported frequent nausea and vomiting at the highest dose. The authors of the pooled analysis concluded that single doses were acceptable in a controlled clinical setting for acute harm in healthy participants. That conclusion applies to screened volunteers with monitoring, and not to unsupervised use or to people with medical conditions.

Effects reported outside the laboratory

The systematic review reports that hypertension, headache, nausea and vomiting were among the effects reported most often. It also describes published case reports of psychotic symptoms and of catatonia after mescaline-containing preparations, and notes that reported effects appeared to depend on setting. Some of these cases involved peyote rather than San Pedro. In the Dutch ceremonial sample, challenging experiences were characterized by physical distress and grief rather than anxiety.

In the online survey, fewer than 1 percent of respondents reported seeking psychiatric services and none reported seeking medical treatment. The authors caution that internet recruitment and recall bias limit this finding, and that Native American and Spanish-speaking respondents were few.

Variable plant material and gaps in the evidence

Mescaline content differed by about two orders of magnitude across the cacti analyzed, so the amount of active alkaloid in a given plant is not fixed. A pharmacology review adds that mescaline is largely excreted unchanged in human urine. The sources reviewed do not report studies in people with heart disease, psychotic disorders or pregnancy, and do not address interactions with medicines, so these questions remain unanswered here.

Care boundary

This information is educational and is not individualized medical advice. Severe or persistent symptoms such as chest pain, very high body temperature, confusion or psychosis call for conventional medical care. The sources reviewed do not support using San Pedro in place of, or in order to delay, assessment and treatment of a medical or psychiatric condition.

Representation in the research

The online survey of mescaline users reported a sample that was predominantly white, male and from North America, with fewer than 10 Native American or Spanish-speaking respondents. Most ethnographic work cited on this page documents healers in northern Peru and southern Ecuador, whereas most controlled and survey data come from European and North American volunteers. The two bodies of evidence therefore describe different people and settings.

Conflicting meanings

A 2025 autoethnographic article in Contemporary Drug Problems examines tensions around San Pedro and peyote, drawing on Indigenous perspectives, therapeutic research, markets and ecology, and describes competing interests in which the powers of medicine and prohibition dominate but meet resistance. Only the abstract could be opened. The sources reviewed did not give verified information on harvest sustainability or on how Andean communities view outside use, so this page does not state a position on either.