A Beginner’s Guide to San Pedro

San Pedro has been in use without interruption for thousands of years. This Andean cactus emerged from mysterious rituals beneath ancient pyramids, adapted to survive Spanish colonialism, and has now spread around the globe as a surprisingly common mescaline-containing ornamental plant.

Originally known as “Huachuma” in Quechua, the native language of the Andes, the first evidence of use is documented by the Chavin culture in Northern Peru. Nobody knows how or why the cactus was used in a pitch-black maze of tunnels beneath pyramids. But it’s safe to assume its consumption was part of the Chavin culture, which went through the trouble to decorate with stone carvings of shamans holding cacti while morphing into jaguars.

Today, San Pedro has continued to spread under the radar. It can be found in North American, European, and Australian gardens. A charming cultivar, San Pedro is easy to propagate and grow with beautiful cream-colored and fragrant flowers. Yet, be warned: if you prepare this cactus for consumption, it becomes a controlled substance.

What is San Pedro?

The columnar cacti first naturally occurred on the Western slopes of the Andes in Ecuador and Northern Peru at 1500-3000 meters in the Andes. Western science recognizes San Pedro as Trichocereus (or sometimes Echinopsis) pachanoi. Close relatives Peruvian Torch (Trichocereus peruvianus,) and Bolivian Torch (Trichocereus bridgesii,) also contain mescaline and are sometimes referred to as San Pedro. However, there are said to be many more types of huachuma in the Andes, often characterized by the number of ridges on the cactus. Four is the luckiest, representing the four directions, while other counts are all reported to have subtly different effects.

Evidence suggests San Pedro was cultivated as early as 200 to 600 BC and selected for its psychoactive effects. Reverence for the plant enabled San Pedro to travel far beyond its natural range. High altitude adaptation means it can survive at -10 ℃, while easily propagated foot-long sections placed in the soil can develop roots in a few weeks. Once established, San Pedro can happily grow about a foot per year, which is also conveniently the average amount of cactus needed for a trip.

San Pedro Cactus Hallucinogenic Properties

The altered state induced by San Pedro is attributed to mescaline, a phenethylamine, in the same class of drugs as MDMA. As a phenethylamine, mescaline has stimulating effects, working on dopamine and adrenaline, alongside serotonin receptors. Dr. Malin Uthuag, author of several papers about mescaline and San Pedro, writes that most psychedelics work on our body’s serotonin system, specifically 5-HT2A serotonin receptors. However, mescaline additionally affects the 5HT2C receptors associated with dopamine and adrenaline. San Pedro cactus contains many alkaloids other than mescaline, some of which were found to be mildly psychoactive by pioneering psychedelic chemist Alexander Shuglin.

This variety of alkaloids gives San Pedro unique effects from peyote or synthesized mescaline. While this chemical soup might sound intimidating, San Pedro is often described as dreamy, and Dr. Uthuag’s surveys confirm mescaline is considered by many a “gentle, euphoric, and bodily/tactile experience.”

The San Pedro Experience

But understanding how San Pedro works is more than skimming a list of neurotransmitters. The real mechanics come from how it’s used. From traditional ceremonies steeped in ritual to hanging out alone with plants in your garden, there is an abundance of ways to take the cactus. Whichever route you choose, be patient: San Pedro can take upwards of two to three hours for full effects to be felt. The experience builds up in waves, and while deep introspection and confusion can occur, the trip often is an energizing and remarkably lucid high lasting for 10 to 14 hours, sometimes more.

Visuals occur, but different from plant medicines like ayahuasca, folks typically remain firmly present in their bodies. Paul, a Brit who has been giving people the cactus in the Sacred Valley of Peru for 18 years in his garden, cautions, “those insights, the colors and all that come, enjoy them. But don’t get lost in them. It’s not the purpose, really.” Instead of seeking visions, many are attracted to San Pedro’s reputation as heart medicine, magnification of natural elements, and kind energy likened to that of a grandfather. Paul explains that “what I like about this plant is it’s regarded as more gentle. It’s subtle; it’s not as dramatic on the visuals.” 

In Paul’s garden, there are no alters, medicine songs, or rituals. Despite years around ritual, both in Peru and years meditating in India, Paul offers a simple introduction and instructions like staying present, focusing inward, and breathing into it. He emphasizes the cactus “is guiding us to step more into the realm of consciousness… and that’s not an intellectual exercise” instead that “the heart is perhaps the portal or an entryway beyond to that which lies beyond the mind.”

What is a San Pedro Ceremony?

While watching hummingbirds in a garden will appeal to some, others find San Pedro’s stimulating and euphoric effects a powerful tool for groups and ceremonies. Traditions exist in Northern Peru, but what an ancient huachuma ceremony looked like is lost. Time and colonialism played roles in the disappearance, with the latter responsible for the switch from “huachuma” to “San Pedro,” which is Spanish for “St. Peter.” Early priests were convinced the cactus gave visions of the devil, yet after its association switched to Saint Peter—said to hold “the keys to heaven”—use continued but with Christian symbols woven into the ceremony.

Evolution is perhaps necessary for any tradition surviving as long as San Pedro. We cannot recreate the old rituals but, instead, listen to the plants that originally taught them. Alonso del Rio is the founder of the Center for Healing and Consciousness Studies, Ayahuasca Ayllu. As an ayahuasquero, musician, and author, del Rio began learning from the cactus at age 15, over forty years ago. During his first trip with friends in a park, he shares he was “lucky to hear the plant.” With no huachumeros in Lima where he grew up, del Rio kept learning from direct experience of the cactus. He would also later study ayahuasca with the Shipibo, and these experiences and knowledge of ancient symbols and myth created a new ceremony. 

In del Rio’s approach, based on the universal symbol of the four directions, participants enter a process he likened to group therapy, but with huachuma. He explains that “expression of ourselves in the middle of the strong effects is different.” Instead of an altar of sacred objects, del Rio process moves participants through the four cardinal points and the associated elements. At each altar, various symbolism guides participants to speak publically, while in the medicine. Del Rio relates how our “history is the same. Many people deal with the same struggles and the same abuse.” While ceremony might not feel natural for everyone, he speaks of “how important it is to heal together.” He is also clear that while drinking San Pedro alone or the popular mountain hikes under the cacti’s influence are not wrong, he sees the power of “ceremony and ritual as a vehicle to focus your energy.” After which, his assistant Francisco Riverola quickly adds, “and everybody cries,” while del Rio nods in agreement.

San Pedro Cactus Side Effects

However, if you choose to drink, it’s important to approach mescaline with mindfulness—as with any mind-altering substance. San Pedro and mescaline are among the weakest psychedelics gram for gram, coming in at five percent the potency of psilocybin. Consuming San Pedro is usually done with a mug of what Paul calls “green goo.” The challenge of getting down bitter, thick mescaline smoothies or dry spoonfuls of cactus powder makes consuming enough of the cactus to cause harm unlikely. 

However, the gentle grandfather spirit of San Pedro isn’t only fractals and connections to your ancestors. Confusion, paranoia, dizziness, and, “la purga” or “the purge,” can occur. Viewed as cleansing from a traditional perspective, vomiting is less common than with ayahuasca—but it does happen. In Paul’s garden, a plastic purge bucket and belly-soothing ginger tea are integral to the experience.

While San Pedro has a long history of safe use, like any psychedelic, it comes with risks. There is always the chance of being destabilized by psychedelic use, particularly if someone has a history of psychosis, bipolar disorder, schizophrenia, and other serious mental health concerns. That being said, San Pedro isn’t considered addictive: quite the opposite. Researchers are exploring mescaline as a potential treatment for addiction.

For those who have had a negative psychedelic experience, it’s important to remember this: Support is available. If you’ve taken mescaline in the United States and are concerned or confused about your experience, you can reach the Fireside Psychedelic Peer Support Hotline at 62-FIRESIDE. The support line is open between 11 am and 11 pm Pacific Standard Time. You can also download the Fireside app to access a chat service. (You can also download DoubleBlind’s resource guide for more information on integrating and processing the psychedelic experience.)

Is San Pedro Cactus Legal?

San Pedro is legal to grow as an ornamental plant in most parts of the world, and some mescaline-containing varieties have been spotted at garden centers. However, as a general rule around the globe, mescaline is a controlled substance. 

The clearest route to connect with the cactus legally is in South America. San Pedro is easy to find at markets or ceremonies in Peru, Bolivia, and Ecuador. Legislation has been passed honoring the plant medicine traditions of indigenous in both Peru and Bolivia. San Pedro can also be consumed in some parts of Europe, notably with Portugal decriminalizing drugs and Spain’s loose and grey area not specifying against consumption. 

When the cactus is harvested and made into tea, it then becomes illegal in the United States, Canada, Australia, and most parts of Europe. San Pedro ceremonies are often held wherever it grows, regardless of legality, yet, underground ceremony in some regions is on the way out. Colorado’s Proposition 122 now allows for the legal use of mescaline (except peyote), and the growing list of jurisdictions in the United States which have legalized entheogenic plants all allow the use of San Pedro.

Huachuma—Medicine of the Heart

San Pedro is one of the oldest plant medicines in the world, with evidence suggesting its use for over ten thousand years. Few traditions have survived so long, yet, San Pedro remains low-key compared to superstars like magic mushrooms and ayahuasca. At the same time, this may be a gift: Not many medicines have the same global reach. You can find San Pedro in jungles, deserts, mountains, and perhaps even Home Depot. As Del Rio puts it: “It likes to grow and likes to help.” And perhaps it is no accident that a medicine of the heart has become embedded so deeply in a global north struggling with disorders of the mind.