The Essential Guide to San Pedro
(Pachanoi, Achuma/Huachuma, Aguacolla, Gigantón, El Remedio, Cactus of the Four Winds)
San Pedro (Trichocereus/Echinopsis pachanoi) is a thin, columnar cactus native to the Andes in South America. It is much faster-growing than peyote, shooting up 12 inches or more in a year and occasionally producing large, white, night-blooming flowers.
Like peyote (and Peruvian torch, among other cacti), San Pedro contains mescaline—one of the longest-studied psychedelics in the world and the first to which that term was applied. Its effects have been described as empathogenic, (similar to MDMA) and potentially life-changing, promoting radical introspection, healing, and a sense of wonder and awe.
Traditionally, as today, San Pedro may be consumed either on its own or with other plants in a ceremonial brew called cimora. While its use as a psychedelic is technically illegal in the US, specimens are widely available for “ornamental purposes.” It can also be found in abundance at the witches’ markets of Peru (as San Pedro or Huachuma), Bolivia (as Achuma), and Ecuador (as Aguacolla or Gigantón).
History & Stats02
San Pedro has been called the materia prima, the primordial soup of the cosmos, and has long been revered by Andean shamans. Remnants of rolled-up San Pedro skins discovered in Peru date their use back to c. 2200 BCE. Later artifacts, including temple stone carvings, textiles, and ceramics, suggest the cactus was in use by successive pre-Columbian cultures, including Cupisnique (1500 BCE), Chavín (1000 BCE), Moche (100-750 AD), and Lambayeque (750-1350 AD). Many of these artifacts associate the sacred cactus with the jaguar, hummingbird, deer, boa, owl, snail, and stylized spirals or steps — symbols thought to represent aspects of the visionary experience itself.
Its magico-religious and medicinal use was suppressed by the Catholic conquistadors, but not nearly as much as peyote’s. Its early association with Christian symbols and holidays appears to have helped; in fact, it may have been strategic. San Pedro curanderismo (folk healing) ceremonies were held on June 24th, the Nativity of Saint John the Baptist, for example, while the name of the plant itself, San Pedro, Spanish for Saint Peter, is thought to imply that, like the Christian saint, the cactus “holds the keys to heaven.” But this foreign context was superimposed onto existing, pre-Hispanic/pre-Columbian ideas. Like Saints Peter and John, San Pedro had long been associated with water, albeit more specifically with the fertility of Pachamama (the ‘earth mother’) and mystical “flows between worlds.” Hence the Ecuadorian name, aguacolla, is thought to have originated with the Spanish word agua (water) and Quechua word colla (queen), or else with another Quechua term denoting something hidden or occult—a “hidden water,” in other words, or a portal to “another world.”
Disembodied travel is a hallmark of traditional use. Some even speculate that the Nazca Lines, the geoglyphs of southern Peru, were used as “sacred maps” for these flights. Wind (symbolized by remolinos, or swirls) is also important to San Pedro, and may be seen as a portent of good health during ceremonies, or as the arrival of the spirit of the plant. This spirit is said to assume various forms when manifesting from the air in this way, including a gringo with blond hair, an Inca prince or princess, an animal (such as a jaguar), or San Pedro/Saint Peter himself.
Prior to the (re-)discovery of San Pedro in 1945, botanists were unaware of any mescaline-containing cacti besides peyote. Although it was found to contain less of the psychedelic compound than peyote (<2% by dry weight and 0.12% fresh), San Pedro still represented a significant alternative source. Yet when mescaline and peyote were banned in the United States in 1970 (with users facing up to 15 years in jail and/or a $25,000 fine), San Pedro appears to have escaped the lawmakers’ notice. People freely went on selling it as a “natural and legal” psychedelic and even mainstream garden centers continued to stock the plant.
Nowadays San Pedro is used more or less as it (evidently) always has been, for spiritual and physical healing. Anthropologists and ethnographers familiar with its cultural context have helped to promote it worldwide.
San Pedro is widely available in the West, but it’s often technically illegal for consumption (see Legality for details). Those who prefer to experience the plant in its native habitat can attend a growing number of specialist ceremonies and retreats in South America.
Fortunately, San Pedro populations in the wild appear to be surviving this increased demand, unlike some other natural medicines (e.g. peyote, kambo)—perhaps because it grows back so rapidly when cut. However, indiscriminate overharvesting in some “psychedelic tourism” regions may prove unsustainable in the long term, especially in the absence of peyote.
San Pedro contains highly variable concentrations of mescaline (0.006-0.14% fresh; 0.1-2.375% dried), densest in the outermost, greenest layer of the flesh. As a phenethylamine, mescaline (like MDMA, 2-CB, and others) is in a different class of psychedelics to the tryptamines (e.g. psilocybin, DMT) and ergolines (e.g. LSD, LSA). The cactus also contains hordenine, anhalonidine, anhalonine, trichocerine, tyramine, and several substituted phenethylamines besides mescaline. While their effects are thought to be secondary or negligible compared to mescaline’s, they may account for some of San Pedro’s purported medicinal benefits. Hordenine, for example, is an antibiotic, and anhalonidine has a mildly sedative effect.
Mescaline binds to virtually all serotonin receptors in the brain but has a stronger affinity for the 1A and 2A/B/C receptors. It is structurally similar to LSD and often used as a benchmark hallucinogen when comparing psychedelics.
Like nearly all hallucinogens, the psychedelic effects of mescaline are likely due to its action on serotonin 2A receptors.
Mescaline also has an affinity for the dopamine receptors, either as a selective reuptake inhibitor or as a dopamine receptor agonist.
Safety and toxicity
Because it’s an internationally controlled substance, research into the harm potential of mescaline, especially long-term, has been limited. That said, a lethal dose has never been identified—probably because it would be too high to happen accidentally. In other words, to the best of our knowledge, nobody has ever died from a mescaline overdose. But that doesn’t mean it’s entirely safe; the “maximum safe dose” is often given as 1000 mg (though it’s unclear where that figure came from).
A 2005 study into the ceremonial use of peyote among Native American populations found there to be no detrimental long-term effects. It should be noted, however, that its use in other contexts may not be as safe (remember: set and setting). However, mescaline appears to present little risk of flashbacks or hallucinogen persisting perception disorder (HPPD). Mescaline has been linked to memory and problem-solving impairments in rats, but only at very high doses (30 mg/kg/day).
Most mescaline goes straight to the liver, so it may not be safe if you have liver problems (although it was given to many chronic, often severely liver-diseased alcoholics in the 1950s and ’60s without any obvious complications). People with colon problems, high blood pressure, heart conditions, diabetes, or mental illness are also advised to be cautious. Although peyote is traditionally consumed by Huichol women during pregnancy, mescaline has been linked to fetal abnormalities and should also be avoided by pregnant or breastfeeding women.
San Pedro may not be safe in combination with MAOIs (natural or synthetic), including the antidepressants phenelzine (Nardil) and tranylcypromine (Parnate). Some use MAOIs like moclobemide (Amira, Aurorix, Clobemix, Depnil, Manerix) to enhance the effects or prevent nausea but they may not be safe for everyone’s biochemistry. In fact, MAOIs may actually increase nausea, or induce it when it wouldn’t otherwise be present.
Non-MAOI (e.g. SSRI) antidepressants may diminish the psychoactive effects, but they do not appear to be physically dangerous in combination with San Pedro.
See FAQ for more on potential drug interactions.
There’s no way to tell simply by looking how much mescaline a cactus contains, which makes finding the right dosage quite tricky—especially given San Pedro’s variability. Just 50g dried cactus material might contain as little as 150mg mescaline (a threshold dose) or as much as 1150mg mescaline (a potential overdose). So it’s best to start with the smallest dose likely to yield any effects (~7g dried; 107g fresh) and trial and error from there. If you’re only using the outermost layer, though, the effects will likely be stronger. One cultivar was found to contain 4.7% mescaline in the dried skins, which is roughly double the whole plant “maximum” of 2.375%.
What to expect
You should start to notice effects within 15-40 minutes of taking San Pedro, but it may take 3 hours to peak. It can take another 3 hours to come down, with the whole experience usually lasting 10 hours or so—although there’s usually some kind of afterglow. Residual stimulation could make it difficult to sleep after the primary effects wear off.
Many people are surprised at how different San Pedro (and mescaline generally) is from other psychedelics they’ve tried. It’s common to feel relaxed and in control, for instance, even while heavily tripping. One user compared its effects to MDMA, but felt they were “more amazing.” “Mescaline didn’t feel like rolling [being high on MDMA],” he said, “Rolling felt like mescaline.” The same user went on to say that it was “like all the best effects from all the drugs all put into one… the great body feeling and incredible empathy and understanding of ecstasy… the focus and energy and drive of acid… the journey effect that I always enjoyed from shrooms… It was the soberest we had ever felt in our life.”
Common visual effects include whirlpools of colored light, flashes in the peripheral vision, kaleidoscopic patterns, and white, ghostlike outlines around people. “Out-of-body” journeys are common, according to curanderos (healers), as is synesthesia (e.g. “feeling” and “smelling” sights and sounds), mild depersonalization, and distortions of spatial awareness. At the same time, ordinary objects in your surroundings may appear more interesting, beautiful, and amazingly mystical—qualities that define the mescaline experience.
Accompanying this may be clear and connected thought, self-realization, empathy, and euphoria. However, “bad trips” and dysphoric symptoms may be more common among people who don’t pay attention to set and setting and/or have histories of mental illness.
Take care to remove hazards, including sharp objects and things you might trip over, before taking San Pedro. It’s also wise to ensure easy access to drinking water, as well as a toilet or bucket in case of purging. A responsible sitter is also a good idea, at least for first timers.
You may want to fast for 12 hours before using San Pedro, or at least take it on an empty stomach to minimize nausea and maximize absorption (although some claim digestion potentiates effects). You may also want to spend a few hours meditating or reflecting on what you hope to learn or heal through the experience. The idea is to “purify” the body and mind/spirit in preparation for taking the medicine.
Many like to experience San Pedro outdoors, in nature. As one user put it, “the domain of this plant is space.” But it’s probably a good idea to have somewhere safe and private nearby, just in case you feel overwhelmed.
“Peruvian torch cactus has 10 times the mescaline of San Pedro”
Adam Gottlieb made this claim in Peyote and Other Psychoactive Cacti (1977), but without any supporting evidence. In Pharmacotheon (1993), Jonathan Ott made a similar claim—that Peruvian torch has the highest concentration of any Trichocereus (/Echinopsis) species—but he seems to have missed opposing evidence.
There’s actually some dispute as to whether “San Pedro” refers solely to T. pachanoi or to a range of Trichocereus (/Echinopsis) species, including T. peruvianus/E. peruviana (Peruvian torch). For clarity, most uses of the term refer to T. pachanoi alone, but it’s common to find other closely related species sold as San Pedro as well.
As for which is the strongest, it appears to be T. pachanoi. Analyses of T. peruvianus have found mescaline concentrations of up to 0.817% (dried whole plant), with some finding none at all. T. pachanoi, by contrast, has been found to contain up to 2.375%. Analyses of the mescaline-rich outer flesh alone have found the difference to be even greater: 0.24-0.25% in dried Peruvian torch skins (or up to 0.5% in the subspecies Puquiensis) and up to 4.7% in T. pachanoi.
It should be noted, however, that mescaline content varies so much in both T. pachanoi and T. peruvianus that differences within each species may sometimes be greater than the differences between them. In other words, some Peruvian torch cuttings may well have ten times the mescaline content of some San Pedro cuttings—just not as a general rule.
San Pedro cleansing ceremonies often last all night and may be repeated over several days. In addition to the sacred cactus, curanderos may administer other plants, including other cacti and succulents, lycopods (clubmosses), datura, brugmansia, and Isotoma/Hippobroma longiflora (aka the “Star of Bethlehem”).
Ceremonies traditionally center on a “healing altar” or mesa, upon which are arranged a selection of “power objects”—ancient artifacts, staffs, stones, crosses, images of saints, and so on. These are usually sorted into three zones or fields (campos) according to their energy alignment—positive (life-giving), negative (death-taking), or neutral. Following purification with a bath of “spiritual flowering” or baño de florecimiento, and often the insufflation of tobacco, patients given San Pedro are diagnosed and treated by the healer. This might involve the invocation of spirits from both Andean and Christian cosmology and the passing of a sword or staff over the patient in the form of a cross. Sometimes a guinea pig is passed over the body instead, then killed and dissected to determine the activity or source of an illness.
Whatever takes place in the ceremony, it is to the plant, as opposed to the healer or shaman, that cures are generally attributed. The healer is merely a facilitator, “activated” by the cactus to stimulate “the five senses of the patient in a familiar cultural environment” using music, perfumes, symbols, and other ritual elements. The traditional ceremony also makes little distinction between the domains of the body and mind. Shamans may recognize the medical causes of disease, and even integrate pharmaceuticals into practice, but they’ll generally look beyond for an underlying spiritual basis. Contemporary practitioners tend to frame this in psychosomatic terms, viewing “illness as a thoughtform” and the “guidance of the plant” as helping patients “to see the origin of [their] own illness without judgements or interpretations from others.”
There are some bold claims made about the curative powers of San Pedro, but unfortunately the evidence is anecdotal. One woman, a cancer patient, is said to have entrusted her fate to the plant and, during the ritual, learned why she had cancer and that she had a choice not to have it anymore. According to the healer, “she decided not to have cancer anymore … [she] realized that life was just too precious once she had seen it through San Pedro’s eyes.”
Recoveries from mood disorders are easier to believe. The same healer claims to have seen victims of sexual abuse overcome their guilt or shame, for instance, by replacing hurtful ideas or “negative winds” with “positive winds” or new insights. As a legal psychedelic in many countries, San Pedro may represent a life-saving alternative to banned substances like psilocybin or LSD—sometimes the only ray of hope for treatment-resistant depression.
In the 1950s and ’60s, mescaline was investigated for its psychotherapeutic potential, particularly in combination with LSD. It was found by some researchers that benefits were correlated with subjects’ willingness to engage with the experience, to face themselves and to act upon the insights received. Interestingly, some of the most significant transformations or breakthroughs came about months after the experience itself, even if the initial psychedelic therapy session seemed to be a failure. Benefits included a greater sense of wellbeing, inner strength, and vitality.
Mescaline, and by extension San Pedro, may also be useful for reliving or recalling repressed memories in a psychotherapeutic context, overcoming addiction, and dealing with chronic pain.
San Pedro ceremonies, traditionally held at night, are said to open the subconscious “like a flower.” Some patients are more susceptible than others, of course, but it’s generally an inward journey. According to Western practitioner Lesley Myburgh, the cactus “helps us to heal, to grow, to learn and awaken, and assists us in reaching higher states of consciousness.” Through her own apprenticeship, which involved twice weekly sessions for years, she “saw all the bad things in [her] life … and was able to let them go.”
Others have had similar results. One user who decided to strip the wallpaper from his walls and paint his story across them was able to bring all of his pain to the surface, manifesting almost without thought his repressed struggle to be free from his mother. He was astounded by the richness of meaning, as well as his own creativity.
In fact, mescaline, like other psychedelics, is well known for enhancing creativity. In one study, a group of 27 men were administered the drug and asked to think about a problem they were facing at work, some of which had persisted for months. Following this single dose of mescaline, almost every participant either solved the problem for themselves or came up with new ways to approach it. As the psychologist Stanley Krippner put it, “to invent something new, one cannot be completely conditioned or imprinted,” and psychedelics like mescaline certainly dissolve preconceptions and elicit fresh perspectives on reality.
Indeed, they may be so fresh that they feel otherworldly. As mentioned, “out-of-body journeys” are common, often to real-world locations—but so is a sense of induction to a “wider, mysterious, but very real [other] world that had been there all along.”
San Pedro can also be helpful for strengthening interpersonal bonds or patching up family relations. Its empathogenic qualities, which it shares with MDMA, instil a “sense of universal understanding, a connection with other people, and the ability to come together and work out problems”—even problems that are usually suppressed. Many remark on a newfound emotional fluency, an ability to express their own emotions and identify the struggles of others. It’s a sense of unity that tends to define the San Pedro experience—unity with oneself, with other people and the natural world, and with all of existence at large.
Mescaline is illegal (Schedule I) in the United States. Of the mescaline-containing cacti, though, only peyote is specifically scheduled as a controlled substance. The key is intent; growing San Pedro and other mescaline-containing cacti besides peyote is perfectly legal as long as there’s no intent to sell, prepare, or consume them as psychedelics. Prosecutions are rare, but they do happen. An Illinois man was, according to Erowid in 2013, sentenced to 2½ years’ imprisonment for possessing (with intent to sell) multiple kilograms of powdered cactus. Smaller amounts for personal use may also be prosecutable. In South Dakota, a man was charged with possession of a controlled substance for having just 30 g dried Peruvian torch.
The situation is similar in Australia, New Zealand, the UK, and Germany, as well as many other European countries—except Switzerland, notably, which specifically prohibits both San Pedro and Peruvian torch. In Canada, where peyote (and only peyote) is specifically exempted from the mescaline ban, prosecutors may need to show even stronger evidence of intent (e.g. to extract mescaline) than elsewhere.
In the Andean countries (e.g. Peru, Ecuador, Bolivia, etc.), San Pedro is generally legal, even as a psychedelic.
Can it be detected in a drug test?
Mescaline can be detected in the urine for 1 to 4 days after use, but it’s not included in either standard or extended drug screens. Virtually all labs require a specific test for the substance, so unless your employer is a real stickler and specifically suspects San Pedro use you should be fine.
Are there psychological risks?
If you follow the 6Ss of psychedelic use and avoid taking San Pedro if you have a personal or family history of mental health issues, there appears to be very little chance of long-term psychiatric difficulties.
Of course, San Pedro can make you feel “crazy” in the short term (acute psychosis), especially if you don’t follow the 6Ss. This is known as a “bad trip” and is unlikely to cause problems in the long term. Learning to handle anxiety and paranoia when it arises will help you get through any challenging experiences.
Are there risks?
Neither San Pedro nor mescaline appear to have caused any deaths—not by their physical action, anyway. As with any psychedelic, risks may arise from a poorly planned set and setting, e.g. hazardous environments, being in public, etc. It may also cause problems for users with mental illness, heart conditions, high blood pressure, and liver issues, as well as pregnant or breastfeeding women. For more information on using San Pedro safely, see the Safety and Toxicity section.
How do I take it?
San Pedro is best taken on an empty stomach as a brew, juice, or dried powder (i.e. in capsules or stirred into water). Expect it to taste bitter, though—perhaps unbearably so. Chasing it down with fruit juice (especially unsweetened grapefruit juice) may help; but folk wisdom holds that “if one’s heart is pure, the bitterness will not be tasted.” In other words, if you’re mindful of the bitterness, experiencing it without resistance, the gag reflex shouldn’t kick in.
Is it legal to grow San Pedro at home?
It’s legal to grow San Pedro in most countries, including the US and UK, but often not for human consumption (see Legality). It’s also very easy to grow from cuttings and can thrive in a variety of conditions—both indoors and out—although it prefers a lot more water than most cacti. You can even graft fresh cuttings together (including cuttings from other species) by securing them for a few days with string. Just be aware, if you’re growing San Pedro for mescaline, that the common horticultural form of T. pachanoi (aka “pachanot”) has little to none of the compound. See here for more info.
Can I microdose with San Pedro?
Yes! See our Essential Guide to Microdosing Mescaline.
Will it produce tolerance?
Tolerance to mescaline builds up almost immediately and takes roughly 7 days of abstinence to return to baseline. There is also a cross-tolerance effect with LSD and other psychedelics. This means they will have diminished effects for up to 7 days after your consumption of mescaline, and vice versa.
Generally, though, mescaline isn’t habit-forming and many find their desire to use it actually diminishes with use over time.
Can I mix it with other drugs?
Anecdotally, people have reported good experiences mixing San Pedro with LSD or cannabis, among other psychoactive drugs. It also appears to be low risk or positively synergistic with psilocybin, DMT, and ketamine. Tripsit has more information on safe drug combinations.
However, it’s always best to err on the side of caution and avoid combining mescaline with any other drug, including prescribed medications (if sensible), at least the first time you take it.
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