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San Pedro Cactus Guide: Effects, Common Uses, Safety

Table of Contents

Echinopsis pachanoi, commonly known as San Pedro, is a cactus that contains a wide variety of psychedelic alkaloids. While the primary active ingredient is Mescaline, this cactus has some minor differences due to the other psychedelic alkaloids it contains. The San Pedro cactus naturally grows throughout the Andes mountains in Argentina, Bolivia, Chile, Ecuador, and Peru.

Also part of the Echinopsis genus is the Bolivian Torch and Peruvian Torch. These cacti are commonly confused with San Pedro due to their similar effects and appearance. They are so similar that they are all referred to as San Pedro in Spanish because of their psychoactive effects. There are however slightly different alkaloid compositions between these three species. So, the psychedelic experience will be different depending on which specific species you take.

Table of Contents

  1. Overview
  2. History
  3. Pharmacology
  4. San Pedro Today
  5. FAQ


San Pedro produces a psychedelic effect when consumed in activating multiple psychoactive compounds within the cactus. The primary active compound is mescaline, so the effects are very similar to pure mescaline but not the same. Due to the wide variety of psychoactive alkaloids contained in the cactus, many users report an effect akin to a stimulant as well as a psychedelic experience. The entire San Pedro experience typically lasts around ten hours.

What is San Pedro 

The San Pedro cactus has been used in healing and religious ceremonies for over 3,000 years by shamans in the Andes mountains. It only grows at specific altitudes, between 6,500 and 10,000 feet, making it difficult to obtain in ancient times. The Andes shamans would grind up the cactus in a ritual bowl until it was a slushy liquid. It would then be passed around to the members of their group that were a part of this ceremony. These ceremonies would last the entirety of the night and sometimes they would hold them multiple days in a row.

“Native Names” 

The most common native name for the San Pedro cactus is materia prima which translates to “the primordial soup of the cosmos.” This name alone shows the importance that the San Pedro cactus carried in the eyes of the Andean shamans. Another name for this cactus is huachuma which translates to “removing the head.” This name comes from the belief that the San Pedro cactus can shed away your predispositions and bring you closer to heaven. Similar to the Spanish translation of San Pedro, Saint Peter was a Catholic Saint believed to hold the keys to heaven. Other names for this cactus include achuma, wachuma, aguacolla, hahuacollay, and giganton.

Scientific Name

San Pedro Icon 2 1

The scientific name for the San Pedro cactus is Echinopsis pachanoi. On average an Echinopsis pachanoi cactus’ chemical composition is roughly 90% water, 0.71% mescaline, and trace amounts of 3,4-DMPEA, 3-methoxytyramine, and tyramine. The other Echinopsis species contain similar amounts of water, but different amounts of psychoactive alkaloids. Echinopsis peruvianus contains 0.3% mescaline, and trace amounts of 3,4-DMPEA, primary and secondary amines, free phenolics, triterpenes/steroids, catechins, 3-methoxytyramine, and tyramine. The Echinopsis lageniformis contains 0.76% mescaline, and trace amounts of 3,4-DMPEA, 3-methoxytyramine, and tyramine. Despite the primary active ingredient in all three of these cacti being mescaline, they will all have slightly different effects due to the various other psychoactive alkaloids they contain.

Forms & Ways of Consumption

As with most psychedelic cacti there are a lot of different ways San Pedro can be consumed. The most common way in modern times is to dry it then grind it up into a powder and either put it in capsules or dissolve it into a drink. Putting the dried powder into a capsule is the easiest method since you won’t have to deal with the bitter taste San Pedro is known for. Stirring it into a drink can also help mask the taste.

A more traditional way of preparing San Pedro is by either brewing it into a tea or grinding it up into a slushy liquid. To prepare a tea or a slushy liquid, first cut it into thin, horizontal slices. It will look similar to a cut up kiwi. Then blend the slices up into a slushy liquid. From here, the slushy pulp can be consumed or it can be boiled down then strained into a tea.

Determining dosage is complicated due to the unknown amount of active alkaloids in the cactus. There can be large variances in the amount of mescaline and the other psychoactive alkaloids within San Pedro. An active dose can be anywhere from 20 to 50 grams of dried cactus skin. To make things even more complicated, the various parts of the cactus also have different concentrations of psychoactive alkaloids. The layer just beneath the skin is considered to have the highest concentration of active compounds.


San Pedro use dates back over 3,000 years with Andean Shamans who would harvest the cactus from the Andes Mountains in Peru, Argentina, Bolivia, Chile, and Ecuador. They would consume the cactus for religious ceremonies that would sometimes last multiple days. The name San Pedro, Spanish for Saint Peter, dates back to the Catholic missionaries. The story goes that God hid the keys to heaven, and Saint Peter found them using the powers of the San Pedro cactus. This is why Saint Peter is known as the Saint that holds the keys to heaven.

Indigenous Uses

Since the beginning of Andean civilization, Andean shamans used the San Pedro cactus as a spiritual tool. They called it materia prima which meant the “primordial soup of the cosmos.” As the name implies, the Andean shamans considered the San Pedro cactus as the original material of the universe. This perfectly describes how important San Pedro was to the Andean shamans. 

These cultures in the Andes Mountains would express the importance of the visionary trips their members would take when ingesting San Pedro through wood carvings, stone sculptures, goldwork, and painted textiles. On these pieces of art, would be images of the visions they saw during their psychedelic experiences. Common symbols would be jaguars, hummingbirds, deer, boa, owls, snails, and psychedelic art. These symbols represent the individual’s guide to the universe.

Laws and Legal Status

The Comprehensive Drug Abuse Prevention and Control Act of 1970 categorized mescaline as a Schedule I substance making it an illegal substance. However, the San Pedro cactus was not classified though is still illegal to possess with the intention of consumption. This means it is legal to cultivate and purchase the cactus so long as it is purely for gardening or decor. This is also the case with most first world countries where it is illegal to possess if the intent is for consumption. The law did leave room for use by the Native American Church in religious ceremonies, but there is some controversy over this as the NAC is not well defined.

The United Kingdom lists mescaline as a schedule A substance. That means, mescaline has no medicinal value according to the government. Australia lists mescaline as a schedule 9 substance making it an illegal substance. But San Pedro may be grown so long as its intended purpose is not for consumption. The Netherlands and Germany are an exception. Pure mescaline and dried mescaline cacti are illegal substances, which includes the San Pedro cactus.


The primary psychoactive compound in the San Pedro cactus is mescaline. But it also contains a wide range of other psychoactive compounds in varying amounts. Mescaline is a psychedelic compound that produces visual and auditory hallucinations as well as a distorted sense of time and an altered thought process. This is caused from the compound’s similarity to the neurotransmitters dopamine and noradrenaline allowing it to bind to the 5-HT2A and 5-HT2C serotonin receptors in the brain.

Echinopsis lageniformis and Echinopsis pachanoi differ from the rest of the Echinopsis genus in that they contain higher concentrations of other alkaloids aside from mescaline. These higher concentrations of other alkaloids makes extracting pure mescaline more difficult, and their effects very different from pure mescaline than other mescaline-containing cacti. There is also some speculation within the psychedelic community that Echinopsis lageniformis contains MAOIs which can prevent the breakdown of mescaline within your body. The purest source to extract mescaline from would be the Echinopsis peruviana due to its relatively low levels of other psychoactive alkaloids. 

It is becoming increasingly difficult to track the alkaloid content in the different species of Echinopsis because breeders have been crossing the lageniformis, pachanoi, and peruviana species. This creates hybrid species that have large variations in their alkaloid content. One of the hybrids from this cross breeding is commonly referred to as pachanot. It is nearly identical to the pachanoi species except it has very low alkaloid content including mescaline. The pachanot is the species that most cactus flower shops in the United States sell as the San Pedro cactus. Due to the low alkaloid content, there will be very little to no psychedelic effect if consumed.


Before we can discuss whether or not San Pedro is toxic, we first need to define what makes a substance toxic. Toxicity is defined based on the levels of exposure required for a substance to cause harm to a human or animal. The level of toxicity is measured based on the dose required to cause harm to a human. Even water can be toxic in too high of a dose and lethal snake venom can be non-toxic in a small enough dose. LD50 is a common measurement of toxicity, which measures the lethal dose for half of the tested organisms.

Currently, no data exists on the toxicity of San Pedro as a whole, but we can look at the toxicity of Mescaline. Unfortunately, Mescaline has not been studied for toxicity in humans either. We can however use a study for an oral dose in rats which established an LD50 of 880mg/Kg which for an average adult of 150 pounds would be 60 grams of pure Mescaline. While these measures help give us an idea of the toxicity of Mescaline, they cannot be relied upon as humans and rats have different metabolisms. Consuming a high quantity of the San Pedro cactus can make the user vomit, referred to as purging in the psychedelic community. This is far less common when consuming pure mescaline.


As with any substances you ingest, interactions with other substances you take will always be a concern. According to medical sources, stimulants are the main type of drug that can cause adverse effects when mixed with San Pedro. Since they both speed up the nervous system, using both of these substances at the same time can cause a dangerously high heart rate and blood pressure. Refer to other interactions in the table below:

TripSit Guide to Drub Combinations Chart


The primary safety concern with San Pedro is mistaking the cactus for a species that is dangerous to ingest. The most common of these dangerous species are within the Euphorbias genus. Even though they aren’t even cacti, some species can look very similar to San Pedro such as Euphorbia ferox and Euphorbia baioensis. They contain a dangerous toxic carcinogen that is lethal in small doses. Native people would use species in the Euphorbias genus to make poisonous arrowheads.

Common Side Effects

According to the Center for Substance Abuse Research, common side effects of San Pedro include:

  • Increased blood pressure and heart rate
  • Loss of appetite
  • Increased body temperature
  • Impaired motor coordination
  • Dilated pupils
  • Heightened senses
  • The perception of seeing music and hearing colors referred to as Synesthesia
  • Hallucinations
  • Loss of your sense of reality

When consuming psychedelic plants, there is a likelihood that they will cause what the psychedelic community calls purging. This typically occurs during the onset of the effects as vomiting or diarrhea. While this won’t occur for every user, being aware of this possibility will reduce the nervousness it could cause during a trip. A psychedelic experience could also make speaking and having sexual intercourse difficult. One should never drive or use heavy machinery while under the effects of a psychedelic substance as it will distort your perception of space and time.

Adverse Effects

As with most psychedelics, a tolerance to Mescaline will build up rapidly. A tolerance can even be noticed after your first use. This means that after repeated use in a short window of time, users will require higher doses to experience the same effects. As mentioned earlier, this tolerance will build up from LSD, Psilocybin, and all other serotonergic substances. This effect is called a cross tolerance. To avoid a cross tolerance when using Mescaline, or any psychedelic, a general rule of thumb in the psychedelic community is to space out your trips by at least a week. Of course, this rule of thumb is largely dependent on the individual.

As with every other psychedelic, mescaline can cause HPPD (Hallucinogen persisting perception disorder). This disorder usually manifests as “visual snow,” which is when you see visual particles in the air blurring your sight. In extreme cases, HPPD can result in full blown hallucinations for prolonged periods of time.

There is a chance that psychedelics such as Mescaline can cause PTSD (Post traumatic stress disorder) during challenging trips. This is why a large portion of the psychedelic community believes it is in your best interest to have an experienced tripsitter who can guide and calm you if you begin having difficulties during a trip.

San Pedro Today

San Pedro has become a collectors cactus in the modern world. There is a strong community of cactus growers who create various breeds of the cactus that take on different shapes, colors, and alkaloid content. They are typically for decorative purposes as an intent to consume San Pedro is illegal in most of the Western world. There has also been a growing trend for retreats in South America where users can experience San Pedro in a traditional setting.


The most popular hybrids within this unique community of cactus growers is Juul’s Giant, Chemical Shaman’s Dick, and SS02. Juul’s Giant is a subspecies of the Echinopsis pachanoi. It has an especially large girth that’s nearly double the size of a standard Echinopsis pachanoi. This subspecies was created in Tom Juul’s backyard garden in San Francisco and all legitimate clones of this subspecies originated there.

Chemical Shaman’s Dick, or CSD, is a subspecies of the Echinopsis lageniformis known for its stunted but “girthy” size. It also has unique spines that are very different from other Echinopsis lageniformis. This gives it a very unique appearance that has grown very popular within the cactus enthusiast community. It has become so popular that there are even shirts available with a picture of the top-down view of the cactus.

The SS02 cactus is also a subspecies of the Echinopsis lageniformis created by Ben Kamm at his nursery Sacred Succulents. It is known for its large size growing up to 16 feet tall and with relatively short spines. The short spines cause it to grow very unique offspring. This is a very hardy subspecies so it is a great option for beginners wanting to get into growing cacti.

Around the World

Another growing trend with the San Pedro cactus are retreats in South America where tourists will attend San Pedro ceremonies. This has become a growing industry in South America. Curious individuals can have a traditional San Pedro experience within Native communities. There is concern that if these retreats grow in scale there will be issues with over-consumption of the plant. This over-consumption happened with the Peyote cactus, resulting in it being classified as an at-risk species. It is still unclear if this will become an issue as the San Pedro grows back at a much faster rate than the Peyote.


Does San Pedro Go Bad?

The San Pedro cactus lasts an extremely long time if properly dried prior to storage. A fresh cactus can grow mold at a similar rate as common fruits and vegetables. The Alkaloids within the San Pedro do not degrade into toxic compounds.

How to Store San Pedro ?

Proper storage of San Pedro includes drying the cactus then storing in a cold, dark, and dry location. When stored properly the cactus can last for thousands of years and still contain Mescaline.

What Does San Pedro Taste Like?

San Pedro has an extremely bitter taste due to the alkaloids it contains. Folklore originating from the Native communities in the Andes Mountains says a pure heart will not taste the bitterness. If you are aware of the bitterness and expect it, it will be less likely you will gag and potentially vomit from the taste.

What Does San Pedro Look Like?

San Pedro has a light to dark green color with a diameter between 2.5 to 6 inches. They typically grow to heights of 10 to 20 feet with multiple branches. The tallest recorded San Pedro cactus grew to 40 feet tall. There are typically between six and eight ribs on a mature cactus. It produces yellow to brown spikes that can be up to an inch long. When it is flowering it grows white flowers at the end of its stems that open up at night. The color and shape of the flower is important in identifying which species the cactus is. After fertilization a San Pedro cactus may produce dark green fruit.

Contributor | Cort Honey

Disclaimer: San Pedro is potentially categorized as an illegal drug. Reality Sandwich is not encouraging the use of this drug where it is prohibited. However, we believe that providing information is imperative for the safety of those who choose to explore this substance. This guide is intended to give educational content and should in no way be viewed as medical recommendations.

If you have relevant information or updates concerning the research and studies of psychedelic substances, please reach out to We appreciate your contribution. –RS

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