San Pedro Cactus (Echinopsis pachanoi, Trichocereus pachanoi)
A plain-language profile of the San Pedro cactus (Echinopsis pachanoi, Trichocereus pachanoi): naming confusion, mescaline content, Andean traditions, risks and what we could verify about its legal status.
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Documented analytical data
Each group below is one study's measurement of the stated specimen or preparation. It is not a typical value for the species or product, varies between specimens, and says nothing about effects or safety. 11 values from 3 sources.
French T, Fontana AJ, LaBudde R, Brunelle SL, Sudberg S. Determination and Confirmation of Psychedelic and Psychoacti... (1 value)
Source: French T, Fontana AJ, LaBudde R, Brunelle SL, Sudberg S. Determination and Confirmation of Psychedelic and Psychoactive Compounds in Botanical Materials by UPLC-ESI-MS/MS: Single-Laboratory Validation. J AOAC Int 2026;109:61-74. DOI 10.1093/jaoacint/qsaf081. Read 2026-10-22. Laboratory: Alkemist Labs, Garden Grove, California, USA. Method: UPLC-ESI-MS/MS, 70% methanol/0.5 M acetic acid extract, diphenhydramine internal standard. Date: not reported in source (paper received 2024-09-13).
| Specimen or preparation | Analyte | Value | What it is | Sample size and scope |
|---|---|---|---|---|
| San Pedro cactus (Trichocereus pachanoi), native reference botanical from the Alkemist Labs Herbarium collection | mescaline | 3.565 g/kg (as reported (g/kg of the test portion of the botanical; moisture state not stated)) | (reported) | 10. dataset (N=10): grand mean of 5 test portions by each of 2 analysts on 2 days |
Lin J, Yang S, Ji J, Xiang P, Wu L, Chen H. Natural or artificial: topographic spatial distribution analysis of mesca... (3 values)
Source: Lin J, Yang S, Ji J, Xiang P, Wu L, Chen H. Natural or artificial: topographic spatial distribution analysis of mescaline in cactus plants by MALDI mass spectrometry imaging. Front Plant Sci 2023;14:1066595. DOI 10.3389/fpls.2023.1066595. Read 2026-10-22. Laboratory: Dept. of Forensic Toxicology, Shanghai Key Laboratory of Forensic Medicine, Academy of Forensic Science, Shanghai, China. Method: varies by row (see source). Date: not reported in source.
| Specimen or preparation | Analyte | Value | What it is | Sample size and scope |
|---|---|---|---|---|
| Trichocereus pachanoi, one whole plant seized by customs, cut into 55 sections; lowest value, in the subterranean stem | mescaline | 0.14 ug/mg (dry weight (lyophilised tissue)) | (reported) | 1. range across 55 sections of one plant (epidermal and fleshy tissue of rib and groove); lower end of range; reported as 0.14 +/- 0.01 |
| Trichocereus pachanoi, same single seized plant; highest value, in the crown | mescaline | 102.6 ug/mg (dry weight (lyophilised tissue)) | (reported) | 1. range across 55 sections of one plant; upper end of range; reported as 102.6 +/- 3.49 |
| Trichocereus pachanoi, spine samples (n=27) along one rib of the same plant: all reported below the detection limit | mescaline | 0.003 ug/mg (dry weight (lyophilised tissue)) | (reported) | 27. detection limit; all 27 spine samples below it; limit of detection; spines below it |
Ogunbodede O, McCombs D, Trout K, Daley P, Terry M. New mescaline concentrations from 14 taxa/cultivars of Echinopsis... (7 values)
Source: Ogunbodede O, McCombs D, Trout K, Daley P, Terry M. New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) ("San Pedro") and their relevance to shamanic practice. J Ethnopharmacol 2010;131:356-362. PubMed 20637277, DOI 10.1016/j.jep.2010.07.021 (Table 2 read in the ful... Laboratory: Sul Ross State University, Alpine, Texas, USA (Dept. of Biology; with Cactus Conservation Institute and California Pacific Medical Center). Method: HPLC-UV (205 nm) after Soxhlet methanol and acid-base extraction; identity checked by GC-MS. Date: not reported in source.
| Specimen or preparation | Analyte | Value | What it is | Sample size and scope |
|---|---|---|---|---|
| E. pachanoi (as named in source), cortical stem chlorenchyma; origin: Hutchison et al. 6212: Rio Mara above Chagual, La Libertad Dept., Peru; grown from cutting | mescaline | 0.82 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
| E. pachanoi (as named in source), cortical stem chlorenchyma; origin: Matucana, Lima Region, Peru; grown from cutting | mescaline | 4.7 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
| E. pachanoi (long spined) (as named in source), cortical stem chlorenchyma; origin: Huancabamba, Piura Region, Peru; grown from seed | mescaline | 1.2 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
| E. pachanoi (short spined) (as named in source), cortical stem chlorenchyma; origin: Huancabamba, Piura Region, Peru; grown from seed | mescaline | 0.54 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
| E. pachanoi complex cf. T. pallarensis Ritter (as named in source), cortical stem chlorenchyma; origin: FR676: Pallar, Ancash Dept., Peru; grown from seed | mescaline | 0.47 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
| E. pachanoi complex cf. T. riomizquensis Ritter (as named in source), cortical stem chlorenchyma; origin: FR856: Chuyllas, Rio Mizque, Prov. Campero, Bolivia; grown from seed | mescaline | 0.4 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
| E. pachanoi cv. Juul's Giant (as named in source), cortical stem chlorenchyma; origin: cultivar; grown from cutting | mescaline | 1.4 % of dry weight (dry weight of cortical stem chlorenchyma tissue (dried ~30 h at room temperature)) | (reported) | one sample per taxon/cultivar described; replicate number not stated. single specimen |
Safety first. San Pedro is not a treatment for any condition. If someone is severely confused, agitated, has chest pain or trouble breathing after taking a cactus or plant, call 911 in the US or Poison Help at 1-800-222-1222. See poisoning: what to do first. This page does not help identify cacti or describe preparation, growing or harvesting.
What San Pedro is
"San Pedro" is a common name for a tall, columnar South American cactus. In older and horticultural literature it is called Trichocereus pachanoi, and later Echinopsis pachanoi. The plant contains mescaline, a naturally occurring alkaloid found in cacti, mainly peyote and cacti of the genus Echinopsis. [1] The plant is not the compound. Mescaline is covered in mescaline: compound guide. Some chemistry literature calls these cacti "wachuma." [2]Accepted name and synonyms
Naming is unsettled, and authorities disagree. In the GBIF Backbone Taxonomy (read 2026-10-22), Echinopsis pachanoi (Britton & Rose) H.Friedrich & G.D.Rowley is a synonym, and the accepted name is Trichocereus macrogonus var. pachanoi (Britton & Rose) Albesiano & R.Kiesling; Trichocereus pachanoi Britton & Rose is also treated as a synonym of T. macrogonus. [3] Other databases may differ; Plants of the World Online could not be read this session (blocked), so the name used by other authorities is not verified. Research papers still often use Echinopsis pachanoi, so all of these names can refer to the same plant. A chemistry review lists Trichocereus pachanoi, T. peruvianus and T. bridgesii together as "wachuma" cacti with high mescaline. [2]Traditions
South American healers have used columnar cacti of this group in traditional medicine. [4] A study with the Saraguro Healers Council in southern Ecuador, where ten recognized healers (yachakkuna) were interviewed in 2010 and 2011, reports the San Pedro cactus among the sacred and psychoactive plants used in their healing system, described as an expression of an Andean people's heritage and ability to survive as a community. [5] That study is the voice of one community; practices differ among peoples and regions, and this page does not reproduce ceremonies. See mescaline-cactus traditional contexts and Indigenous traditions, ethics and conservation.What the chemistry shows
A laboratory study of 14 taxa and cultivars of this group found all contained mescaline in stem tissue, with concentrations spanning two orders of magnitude across the plants, and the plants with the highest mescaline, particularly E. pachanoi from Peru, were the ones most associated with documented shamanic use. [4] Those were measurements on specific cloned plants in one laboratory, so they should not be read as a typical strength for San Pedro. This site gives no potency figure and no comparison with other substances.What research shows
Evidence labels: insufficient evidence, Proper evidence not found.- Effects of mescaline. In people it can cause euphoria, hallucinations and psychosis-like effects. [1][6]
- San Pedro as a treatment: Proper evidence not found. We searched PubMed for trials of San Pedro or its preparations in people and found none in what we read. Reviews of mescaline describe clinical potential as unproven, and research has been limited since the early 1970s. [1]
Risks and special groups
- Mescaline belongs to the psychedelic group, which NIDA says can bring on vivid visions and affect a person's sense of self. [7]
- A pharmacology review reports a stimulant-like (sympathomimetic) body pattern and psychosis-like intoxication states. [6]
- Heart disease: data are lacking in people with cardiovascular disease. [8]
- Psychosis or bipolar disorder: people with these are excluded from modern psychedelic research as a precaution. [7]
- Pregnancy: effects of psychedelic drugs are not well understood. [7]
- Medicines: check with a prescriber or pharmacist: how interactions work. Do not stop prescribed medicines on your own.
Legal status
Not legal advice; laws change. The US federal Schedule I list (21 CFR 1308.11, read 2026-10-22) names mescaline and peyote (Lophophora williamsii). The text of that list does not name San Pedro or the genera Echinopsis or Trichocereus. [9] We did not read any regulator page on how the cactus itself is treated in the US, Peru, Ecuador or elsewhere, and a plant not being named does not mean it is permitted: not verified. The Native American Church exemption applies to peyote only. [10] See legal status by country and peyote vs San Pedro.Frequently asked questions
Is San Pedro the same as peyote?
No. They are different cacti, though both contain mescaline. [1]
What is the correct scientific name?
It depends on the database. GBIF lists Echinopsis pachanoi as a synonym of Trichocereus macrogonus var. pachanoi. [3]
Is San Pedro legal?
Not verified. US federal rules name mescaline and peyote but not San Pedro; this is not a statement that the cactus is permitted. [9]
Does San Pedro treat any condition?
Proper evidence not found in what we read. [1]
Is the mescaline content the same in every plant?
No. One laboratory study found a wide range across 14 taxa and cultivars. [4]
References
- Vamvakopoulou IA et al. Mescaline: The forgotten psychedelic. Neuropharmacology. 2023;222:109294. Read 2026-10-22 (abstract on PubMed).
- Dark Classics in Chemical Neuroscience: Mescaline. ACS Chem Neurosci. 2018. Read 2026-10-22 (abstract on PubMed).
- GBIF Secretariat, GBIF Backbone Taxonomy, Echinopsis pachanoi (synonym) and Trichocereus macrogonus var. pachanoi. Read 2026-10-22.
- Ogunbodede O et al. New mescaline concentrations from 14 taxa/cultivars of Echinopsis spp. (Cactaceae) ("San Pedro") and their relevance to shamanic practice. J Ethnopharmacol. 2010;131(2):356-62. Read 2026-10-22 (abstract on PubMed).
- Traditional medicine applied by the Saraguro yachakkuna: a preliminary approach to the use of sacred and psychoactive plant species in the southern region of Ecuador. J Ethnobiol Ethnomed. 2014. Read 2026-10-22 (abstract on PubMed).
- Dinis-Oliveira RJ et al. Pharmacokinetic and Pharmacodynamic Aspects of Peyote and Mescaline: Clinical and Forensic Repercussions. Curr Mol Pharmacol. 2019;12(3):184-194. Read 2026-10-22 (abstract on PubMed).
- National Institute on Drug Abuse, Psychedelic and Dissociative Drugs. Read 2026-10-22.
- Wsol A. Cardiovascular safety of psychedelic medicine: current status and future directions. Pharmacol Rep. 2023;75(6):1362-1380. Read 2026-10-22 (abstract on PubMed).
- US Electronic Code of Federal Regulations, 21 CFR 1308.11 Schedule I. Read 2026-10-22.
- US Electronic Code of Federal Regulations, 21 CFR 1307.31 Native American Church. Read 2026-10-22.