San Pedro

What Is San Pedro?

San Pedro is a tall, fast-growing columnar cactus of the Andes, and the sacred plant huachuma of Andean healing ceremonies. Its stem contains mescaline, the psychedelic alkaloid also found in peyote.

Echinopsis pachanoi is native to the dry mountain shrublands of Peru and southern Ecuador, at 2,000–3,200 m ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}. It grows into a many-stemmed, tree-like cactus 3–6 m tall ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}. Archaeological evidence of its ceremonial use in Peru goes back to at least 1500 BC ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}, and it is still grown around houses there and planted as an ornamental worldwide ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

Two controlled trials in healthy volunteers have measured the effects of pure mescaline, and surveys of people who have taken it report improvements in mood, anxiety and substance use ^{2,3,6Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →Reference 3Ley L et al. · 2023RCTComparative acute effects of mescaline, LSD, and psilocybin in a randomised, double-blind, placebo-controlled cross-over study in healthy participantsView study →Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →}.

San Pedro is often confused with its close relative the Peruvian torch cactus (Trichocereus peruvianus) ^{17Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

How Is San Pedro Used?

• Stem decoction — the ceremonial preparation. The green stem is sliced and boiled for hours into a bitter drink.
• Chopped young stems — sold in markets in Ecuador, northern Peru and Bolivia ^{17Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.
• Stem-tip poultice and flower infusion — minor folk remedies in Bolivia and Ecuador ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.
• Living plant — grown as an ornamental, a hedge and a living fence ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

Traditional Uses

Andean Ceremonial Healing

San Pedro is the huachuma or wachuma of the Andes. Mescaline-containing cacti have been used in Peru, Mexico and the United States for more than 6,000 years ^{8Reference 8Cassels BK · 2018ReviewDark Classics in Chemical Neuroscience: Mescaline — reviewView study →}, and archaeological evidence for San Pedro’s own ritual use in Peru dates to at least 1500 BC ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

In the classic ceremony a curandero leads a night-long healing rite. The stem is boiled for hours into a bitter decoction, and the cactus is placed on the mesa, the healer’s altar. The rites treat enchantment and bad luck ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

Healers recognise several kinds of San Pedro by the number of ribs. Seven-ribbed plants are the most common. Four-ribbed plants are rare and held to have special power, each rib standing for one of the “four winds” of the cardinal directions ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}. Plants from the highlands are said to be the most potent ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

Spanish chroniclers of the 16th century called these cacti “diabolic”, and their use was prohibited, but it continued to the present day ^{8Reference 8Cassels BK · 2018ReviewDark Classics in Chemical Neuroscience: Mescaline — reviewView study →}.

Andean Folk Medicine

In La Paz and El Alto in Bolivia, a poultice of the mashed and heated stem tips is used for mumps, wounds and acne. In Ecuador an infusion of the flowers is taken for nervous conditions ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

Indications

• Ceremonial and spiritual healing [stem decoction; Andean curanderismo]
• Mumps, wounds and acne [heated stem-tip poultice; Bolivian folk use]
• Nervous conditions [flower infusion; Ecuadorian folk use]
• Low mood, anxiety and problem substance use [cactus or mescaline; contemporary use] ⚠Caution: The human evidence is self-report from surveys of people who took mescaline. No controlled trial in patients exists ^6,7.

Botany

San Pedro is a large, many-stemmed columnar cactus in the cactus family (Cactaceae). It forms a small tree 3–6 m tall, with upright, flexible branches that rise mostly from the base ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

The stems are 6–15 cm thick. They are pale green to blue-green and slightly waxy when young, turning dark green with age ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}. Each stem has 4–8 broad, rounded ribs, usually 5–7, with a deep notch above each areole ^{17Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

The spines are highly variable and often absent. When present there are three to seven, dark yellow to light brown, the longest 1–2 cm ^{17Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

The flowers are very large, white and fragrant, up to 22 cm across. They open at night and stay open through the following day. Their outer segments are brick red. The buds form in the areoles near the tips of the branches, and the flower tube and fruit are covered in scales and black, curled hairs ^{17Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}. The fruit is oblong and dark green, 5–6 cm long ^{17Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

Botanists who divide the broad genus Echinopsis place San Pedro in Trichocereus, as Trichocereus macrogonus var. pachanoi ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

Distribution

San Pedro grows wild in the Andes from Peru to southern Ecuador, in dry shrublands at 2,000–3,200 m ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

It is widely grown as an ornamental and in rituals, and is planted around houses in Peru and as hedges in tropical gardens worldwide ^{16,17Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →Reference 17LLIFLE — Encyclopedia of Living Forms · 2005Cereus pachanoi (Echinopsis pachanoi) — species description. https://llifle.com/Encyclopedia/CACTI/Family/Cactaceae/8472/Cereus_pachanoiView study →}.

Sourcing: San Pedro is widely cultivated and easy to grow from cuttings. The IUCN assessed it in 2017 as Least Concern, with a wide range and a stable population. Its use as an ornamental and in rituals is not considered a threat, because the plant is also cultivated for both ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

Growing Conditions

Cultivation snapshot for San Pedro

• Full sun for the best form and color.
• Because it is a montane rather than desert cactus, it tolerates and even enjoys more water than most cacti during active growth — but still needs fertile, sharply free-draining soil (amended with pumice or perlite) to avoid rot.
• One of the fastest-growing columnar cacti, often adding around 30 cm a year.
• Very easy from stem cuttings (which clone the parent) as well as seed, and hardier than most cacti — tolerating brief lows near −9 °C (roughly USDA zones 8b–10).

Grow it yourself

Farm Wiki is our cultivation-focused sister site, also run by Justin Cooke.

How to growComing soon

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Pharmacology & Research

San Pedro is studied through its main alkaloid, mescaline (3,4,5-trimethoxyphenethylamine), a classic serotonergic psychedelic ^{5,8Reference 5Vamvakopoulou IA et al. · 2023ReviewMescaline: the forgotten psychedelic — reviewView study →Reference 8Cassels BK · 2018ReviewDark Classics in Chemical Neuroscience: Mescaline — reviewView study →}.

Since 2020 a research group in Basel has run two randomised, placebo-controlled trials of mescaline in healthy volunteers. They measured its dose-dependent effects, its pharmacokinetics and its action at the 5-HT2A receptor ^{2,3,4Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →Reference 3Ley L et al. · 2023RCTComparative acute effects of mescaline, LSD, and psilocybin in a randomised, double-blind, placebo-controlled cross-over study in healthy participantsView study →Reference 4Mueller L et al. · 2025Pharmacokinetics, pharmacodynamics and urinary recovery of oral mescaline hydrochloride in healthy participants — phase I pharmacokinetic analysisView study →}.

The therapeutic signals for anxiety, depression and addiction come from animal studies, surveys of people who took mescaline, and a 2026 systematic review of reports ^{5,6,7Reference 5Vamvakopoulou IA et al. · 2023ReviewMescaline: the forgotten psychedelic — reviewView study →Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →Reference 7Shaw J et al. · 2026Systematic reviewThe ethnopharmacological use of mescaline for psychiatric disorders: a systematic reviewView study →}.

1. Psychedelic / 5-HT2A Activity

This is the only property of mescaline established under controlled conditions.

In a double-blind, placebo-controlled crossover study, 16 healthy volunteers took 100, 200, 400 and 800 mg of mescaline. Doses above 100 mg produced dose-dependent psychedelic effects. The effects lasted from 6.4 hours at 100 mg to 14 hours at 800 mg. Blood pressure rose at doses above 100 mg, and heart rate rose with dose ^{2Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →}.

Giving the 5-HT2A blocker ketanserin with 800 mg of mescaline reduced and shortened the effects to the level of the 100–200 mg doses. This points to the 5-HT2A receptor as the main site of action ^{2Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →}. Mescaline also acts at 5-HT2C, α-adrenergic and dopamine receptors ^{5Reference 5Vamvakopoulou IA et al. · 2023ReviewMescaline: the forgotten psychedelic — reviewView study →}.

A crossover trial in 32 healthy volunteers compared 300 or 500 mg of mescaline with LSD and psilocybin. At equally strong doses the experiences were alike. Mescaline lasted longest, 11.1 hours on average, against 8.2 hours for LSD and 4.9 hours for psilocybin ^{3Reference 3Ley L et al. · 2023RCTComparative acute effects of mescaline, LSD, and psilocybin in a randomised, double-blind, placebo-controlled cross-over study in healthy participantsView study →}.

Pooled modelling of 105 doses in 49 people showed that exposure rose in step with dose, with a peak at about 2 hours and a half-life of 3.5 hours. About half of each dose (53%) left the body unchanged in the urine ^{4Reference 4Mueller L et al. · 2025Pharmacokinetics, pharmacodynamics and urinary recovery of oral mescaline hydrochloride in healthy participants — phase I pharmacokinetic analysisView study →}.

Gap: all of this used synthetic mescaline hydrochloride at measured doses — no controlled study has dosed the San Pedro decoction itself, whose alkaloid content is uncontrolled ^{1Reference 1Ogunbodede O et al. · 2010New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) (“San Pedro”) and their relevance to shamanic practice — analytical (HPLC) studyView study →}.

2. Anxiolytic

A 2023 review reports anxiolytic-like effects of mescaline in animals, together with more social behaviour and more movement ^{5Reference 5Vamvakopoulou IA et al. · 2023ReviewMescaline: the forgotten psychedelic — reviewView study →}.

In humans the evidence is self-report. In an anonymous online survey of 452 people who had taken mescaline outside a clinic, 68–86% of those with a history of anxiety, depression, PTSD or substance use disorder reported improvement after their most memorable experience. Those who improved reported stronger mystical-type experiences, psychological insight and ego dissolution ^{6Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →}.

Gap: no randomised or open-label trial in patients exists, and the human evidence is retrospective self-report ^{6Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →}.

3. Antidepressant

In the same survey, a majority of respondents with a history of depression reported improvement after mescaline. Psychological insight during the experience was linked to higher odds of improvement ^{6Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →}.

A 2026 systematic review found 66 relevant studies, of which only 10 could be analysed. They reported improvements in depression scales, well-being, nicotine dependence, alcohol use and obsessions, but the literature was too limited and variable for firm conclusions ^{7Reference 7Shaw J et al. · 2026Systematic reviewThe ethnopharmacological use of mescaline for psychiatric disorders: a systematic reviewView study →}.

A comparative review found that evidence for therapeutic use of the psychedelics studied remains scarce, apart from psilocybin for depression ^{9Reference 9Holze F et al. · 2024ReviewSerotonergic psychedelics: a comparative review of efficacy, safety, pharmacokinetics and binding profile — reviewView study →}.

Gap: there is no mescaline-specific efficacy trial for depression ^{7,9Reference 7Shaw J et al. · 2026Systematic reviewThe ethnopharmacological use of mescaline for psychiatric disorders: a systematic reviewView study →Reference 9Holze F et al. · 2024ReviewSerotonergic psychedelics: a comparative review of efficacy, safety, pharmacokinetics and binding profile — reviewView study →}.

4. Anti-Addiction

Classic psychedelics, mescaline among them, have been used to support addiction treatment from ceremonial settings to clinical trials. That ceremonial record includes peyote (Lophophora williamsii), a different cactus ^{10Reference 10Rabinowitz J et al. · 2022ObservationalThe association between naturalistic use of psychedelics and co-occurring substance use disorders — observational (cross-sectional) studyView study →}.

In a 2017 US survey of 56,276 people, past use of peyote or mescaline was linked to lower odds of substance use disorder in the past year (adjusted odds ratio 0.68). Past use of LSD or psilocybin was linked to higher odds. The authors could not say whether the difference came from the drugs themselves or from the ceremonial settings in which peyote is usually taken ^{10Reference 10Rabinowitz J et al. · 2022ObservationalThe association between naturalistic use of psychedelics and co-occurring substance use disorders — observational (cross-sectional) studyView study →}.

A later national analysis found that psilocybin and LSD use were linked to higher rates of cannabis use disorder; it did not report a link for mescaline ^{11Reference 11Zech JM et al. · 2025ObservationalAssociations between psychedelic use and cannabis use disorder in a nationally representative sample — observational studyView study →}.

Gap: the data are observational and cannot establish cause and effect ^{10,11Reference 10Rabinowitz J et al. · 2022ObservationalThe association between naturalistic use of psychedelics and co-occurring substance use disorders — observational (cross-sectional) studyView study →Reference 11Zech JM et al. · 2025ObservationalAssociations between psychedelic use and cannabis use disorder in a nationally representative sample — observational studyView study →}.

5. Post-Traumatic Stress

In the naturalistic survey, respondents with a history of PTSD were among those reporting improvement after mescaline. This is a small, self-selected group answering from memory ^{6Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →}.

Gap: no animal model, mechanistic study or clinical trial has examined mescaline for trauma-related disorders ^{6Reference 6Agin-Liebes G et al. · 2021ObservationalNaturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional surveyView study →}.

Mechanisms

Mescaline is a phenethylamine that acts as an agonist at serotonin 5-HT2A and 5-HT2C receptors. Its psychedelic effects are attributed mainly to 5-HT2A, and it also binds α-adrenergic and dopamine receptors ^{5,8Reference 5Vamvakopoulou IA et al. · 2023ReviewMescaline: the forgotten psychedelic — reviewView study →Reference 8Cassels BK · 2018ReviewDark Classics in Chemical Neuroscience: Mescaline — reviewView study →}.

About half of an oral dose leaves the body unchanged in the urine, and much of the rest as its main metabolite, 3,4,5-trimethoxyphenylacetic acid ^{4Reference 4Mueller L et al. · 2025Pharmacokinetics, pharmacodynamics and urinary recovery of oral mescaline hydrochloride in healthy participants — phase I pharmacokinetic analysisView study →}.

Clinical Trials

Two completed phase I trials in healthy volunteers, both from one Basel group, measured mescaline’s acute effects, pharmacokinetics and receptor action. No controlled trial in patients has been completed, none is registered, and none used San Pedro itself.

Last checked: July 2026.

Phytochemistry

The main alkaloid is mescaline, measured in the green outer tissue of the stem ^{1,14Reference 1Ogunbodede O et al. · 2010New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) (“San Pedro”) and their relevance to shamanic practice — analytical (HPLC) studyView study →Reference 14Moreno-Pedraza A et al. · 2019Elucidating the distribution of plant metabolites from native tissues (mescaline mapped in an Echinopsis pachanoi cross-section) — analytical imaging studyView study →}. Across 14 San Pedro-type cacti (species and cultivars of Echinopsis), mescaline ranged from 0.053% to 4.7% of dry weight, with E. pachanoi from Peru among the richest ^{1Reference 1Ogunbodede O et al. · 2010New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) (“San Pedro”) and their relevance to shamanic practice — analytical (HPLC) studyView study →}. Selected cultivars of San Pedro reach up to 5% ^{16Reference 16Useful Tropical PlantsTrichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status)View study →}.

3-Methoxytyramine has been isolated from the stem alongside mescaline ^{18Reference 18Crosby DM · 1973Cactus alkaloidsView study →}. Lophophine, homopiperonylamine and lobivine are minor phenethylamines also found in peyote ^{19Reference 19Bruhn JG et al. · 2008Ecstasy analogues found in cacti — analyticalView study →}. The protoalkaloids hordenine and tyramine and the isoquinoline anhalonidine are also listed among its constituents.

Mescaline is also a major alkaloid of the related wachuma cacti T. peruvianus and T. bridgesii, and of peyote ^{8Reference 8Cassels BK · 2018ReviewDark Classics in Chemical Neuroscience: Mescaline — reviewView study →}.

Constituent Summary

Amounts are percentages of dry stem.

Dosage

Every controlled dose in the research is synthetic mescaline hydrochloride, not the cactus.

Traditional Dosage

Safety & Pregnancy

San Pedro produces a long mescaline experience. The main risks are interactions with serotonergic and MAOI drugs and strain on the heart, and the mescaline content of the cactus varies widely from plant to plant ^{1,2Reference 1Ogunbodede O et al. · 2010New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) (“San Pedro”) and their relevance to shamanic practice — analytical (HPLC) studyView study →Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →}.

Full Safety & Interactions Detail

Duration. Mescaline’s effects last from about 6 hours at low doses to 14 hours at high ones ^{2,3Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →Reference 3Ley L et al. · 2023RCTComparative acute effects of mescaline, LSD, and psilocybin in a randomised, double-blind, placebo-controlled cross-over study in healthy participantsView study →}.

Drug interactions. Mescaline acts on serotonin and adrenaline receptors, so combining it with MAOIs, SSRIs or other serotonergic drugs risks serotonin toxicity. The tyramine-type amines in the cactus may add a hypertensive risk with MAOIs.

Heart. Mescaline raises blood pressure at doses above 100 mg and raises heart rate with dose ^{2Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →}. Heart disease is a reason to avoid it.

Mental health. A personal or family history of psychosis or bipolar disorder is a reason to avoid it. A 2026 review of psychedelics found mood switches, including hypomania or mania, in 5.8% of people in controlled psilocybin trials and 30% in naturalistic studies of people with bipolar disorder. The risk was higher with bipolar I disorder, a family history, use with other drugs, and unsupervised use ^{13Reference 13Eskinazi M et al. · 2026Meta-analysisPsychedelic-induced hypomania and mania: a systematic review and meta-analysisView study →}.

Nausea. Nausea and vomiting are common, and were frequent at 800 mg ^{2,7Reference 2Klaiber A et al. · 2024RCTAcute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjectsView study →Reference 7Shaw J et al. · 2026Systematic reviewThe ethnopharmacological use of mescaline for psychiatric disorders: a systematic reviewView study →}.

Dose. Mescaline content varies widely between plants, so the dose delivered by raw cactus is hard to predict ^{1Reference 1Ogunbodede O et al. · 2010New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) (“San Pedro”) and their relevance to shamanic practice — analytical (HPLC) studyView study →}.

Law. The living cactus is often legal to grow as an ornamental, while extracting or preparing mescaline for consumption is typically prohibited. Check local law.

References

1. Ogunbodede O, McCombs D, Trout K, Daley P, Terry M. (2010). New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) (“San Pedro”) and their relevance to shamanic practice — analytical (HPLC) study. J Ethnopharmacol. https://pubmed.ncbi.nlm.nih.gov/20637277/
2. Klaiber A, Schmid Y, Becker AM, et al. (2024). Acute dose-dependent effects of mescaline in a double-blind, placebo-controlled, randomised study in healthy subjects. Transl Psychiatry. https://pubmed.ncbi.nlm.nih.gov/39349427/
3. Ley L, Holze F, Arikci D, et al. (2023). Comparative acute effects of mescaline, LSD, and psilocybin in a randomised, double-blind, placebo-controlled cross-over study in healthy participants. Neuropsychopharmacology. https://pubmed.ncbi.nlm.nih.gov/37231080/
4. Mueller L, Klaiber A, Ley L, et al. (2025). Pharmacokinetics, pharmacodynamics and urinary recovery of oral mescaline hydrochloride in healthy participants — phase I pharmacokinetic analysis. Clin Pharmacokinet. https://pubmed.ncbi.nlm.nih.gov/40658345/
5. Vamvakopoulou IA, Narine KAD, Campbell I, et al. (2023). Mescaline: the forgotten psychedelic — review. Neuropharmacology. https://pubmed.ncbi.nlm.nih.gov/36252614/
6. Agin-Liebes G, Haas TF, Lancelotta R, et al. (2021). Naturalistic use of mescaline is associated with self-reported psychiatric improvements and enduring positive life changes — observational cross-sectional survey. ACS Pharmacol Transl Sci. https://pubmed.ncbi.nlm.nih.gov/33860184/
7. Shaw J, Yong A, Lee J, et al. (2026). The ethnopharmacological use of mescaline for psychiatric disorders: a systematic review. Int J Mol Sci. https://pubmed.ncbi.nlm.nih.gov/41977267/
8. Cassels BK, Sáez-Briones P. (2018). Dark Classics in Chemical Neuroscience: Mescaline — review. ACS Chem Neurosci. https://pubmed.ncbi.nlm.nih.gov/29847089/
9. Holze F, Singh N, Liechti ME, et al. (2024). Serotonergic psychedelics: a comparative review of efficacy, safety, pharmacokinetics and binding profile — review. Biol Psychiatry Cogn Neurosci Neuroimaging. https://pubmed.ncbi.nlm.nih.gov/38301886/
10. Rabinowitz J, Lev-Ran S, Gross R. (2022). The association between naturalistic use of psychedelics and co-occurring substance use disorders — observational (cross-sectional) study. Front Psychiatry. https://pubmed.ncbi.nlm.nih.gov/36704738/
11. Zech JM, Yaden DB, Jones GM. (2025). Associations between psychedelic use and cannabis use disorder in a nationally representative sample — observational study. Drug Alcohol Depend. https://pubmed.ncbi.nlm.nih.gov/39586127/
12. Xu T, Wong S, Le GH, et al. (2026). Cardiac consequences associated with psychedelic use: 5-HT2B-mediated valvular heart disease — systematic review. Pharmacopsychiatry. https://pubmed.ncbi.nlm.nih.gov/41643722/
13. Eskinazi M, Nasserdine R, Cusin RM, et al. (2026). Psychedelic-induced hypomania and mania: a systematic review and meta-analysis. Mol Psychiatry. https://pubmed.ncbi.nlm.nih.gov/42215638/
14. Moreno-Pedraza A, Rosas-Román I, Garcia-Rojas NS, et al. (2019). Elucidating the distribution of plant metabolites from native tissues (mescaline mapped in an Echinopsis pachanoi cross-section) — analytical imaging study. Anal Chem. https://pubmed.ncbi.nlm.nih.gov/30636413/
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16. Useful Tropical Plants. Trichocereus macrogonus pachanoi (San Pedro cactus) — species profile (range, habitat, uses and IUCN status). https://tropical.theferns.info/viewtropical.php?id=Echinopsis+pachanoi
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