San Pedro cactus (Echinopsis pachanoi) has been used in Andean healing ceremonies for at least 2,000 years, and the basic preparation method hasn’t changed much: remove the outer skin, isolate the green flesh, and simmer it in water for hours. The process is simple but labor-intensive, and the resulting brew is notoriously bitter and hard on the stomach.
Before preparing San Pedro, understand the legal landscape. In most countries, growing the cactus as an ornamental plant is legal. Extracting or preparing mescaline for consumption is a separate matter entirely. In the United States, mescaline is a Schedule I controlled substance. The United Kingdom allows possession of the living cactus but considers drying or cutting it into consumable pieces a criminal act. Australia, Canada, New Zealand, Sweden, and Slovenia follow similar logic: the plant is legal to grow, but preparing it for ingestion crosses a legal line. Know the laws where you live.
Selecting and Harvesting the Cactus
The active compounds in San Pedro concentrate in the dark green layer of flesh just beneath the waxy outer skin. The white inner flesh and the woody core at the center contain very little of these compounds, so the goal of preparation is to isolate that green layer as efficiently as possible.
Mature columns, typically at least a few years old and around 3 inches in diameter, are preferred. Thicker, older growth tends to have a higher concentration of alkaloids than thin, fast-growing tips. A single foot-long section of cactus is a common starting amount, though potency varies widely between individual plants, growing conditions, and even seasons.
Removing the Skin and Core
Start by cutting away the spines with a sharp knife. Some people freeze the cactus overnight before processing, which softens the waxy outer layer and makes it easier to peel away from the green flesh underneath.
Slice the column lengthwise in half, then remove the white woody core running through the center. You can cut the core out in a V-shape or simply pull it away. Next, take a spoon or knife and scrape the dark green flesh away from the outer waxy skin. This step matters because the skin itself doesn’t contain meaningful amounts of the active compounds, and leaving it in adds plant material that contributes to nausea without adding potency. Similarly, trim away as much of the pale inner flesh as you reasonably can. The result should be a pile of dark green, slimy cactus flesh.
The Traditional Brewing Method
In Northern Peru, healers have long prepared San Pedro as a slow-cooked decoction, sometimes called “cimora.” Traditional recipes occasionally include other plants like tobacco or angel’s trumpet, but the basic preparation uses only cactus and water.
Place the green flesh in a large pot and cover it with water. Bring it to a gentle boil, then reduce to a low simmer. The standard approach is to cook for several hours, often anywhere from 4 to 8 hours, adding water as it evaporates. The goal is to break down the plant cells and draw the alkaloids into the liquid. Some people mash or blend the cactus before cooking to increase surface area and speed up the process.
After the long simmer, strain the liquid through cheesecloth or a fine mesh strainer, squeezing the pulp to extract as much liquid as possible. You can then reduce the strained liquid further by continuing to simmer it down to a smaller, more concentrated volume. This makes it easier to drink, though it does nothing to improve the taste, which is intensely bitter and somewhat mucilaginous.
Adding Acid to the Water
A common practice is adding citric acid or lemon juice to the cooking water. The reasoning is that an acidic environment helps pull alkaloids out of plant material more efficiently. Research published in the Journal of Natural Products tested citric acid against hydrochloric acid for extracting mescaline from San Pedro tissue and found them equally effective. This suggests that adding citric acid to your cooking water is at least as good as harsher laboratory acids for this purpose, and it’s far more accessible. A few tablespoons of lemon juice or a teaspoon of citric acid powder per pot of water is a typical amount.
Dried Powder as an Alternative
Some people skip the brewing step and instead dry the green flesh for later use. After separating the green layer from the skin and core, slice it thin and dehydrate it using a food dehydrator, an oven on its lowest setting, or simply by leaving it in the sun. Once fully dry, grind it into a fine powder.
The advantage of powder is storage and portability. It can be stirred into juice or packed into capsules to avoid the taste. The disadvantage is that you’re consuming all the plant fiber, which tends to make nausea worse than a strained liquid would. Removing the waxy skin and white flesh before drying helps minimize this by concentrating the active material and reducing the total volume of plant matter you need to ingest.
Nausea and How to Reduce It
Gastrointestinal distress is the most common side effect of consuming San Pedro. Nearly everyone experiences some degree of nausea, and vomiting during the first hour or two is typical. This is partly because the cactus contains a large amount of plant alkaloids, mucilage, and fiber that irritate the stomach lining.
Several practical steps can reduce the severity. Straining the brew thoroughly removes insoluble fiber that the stomach struggles to process. Reducing the liquid to the smallest drinkable volume means less total fluid sitting in your stomach. Fasting for at least 4 to 6 hours beforehand is standard practice and mirrors the dietary restrictions common in traditional ceremonial contexts, where participants avoid heavy foods, sugar, alcohol, and processed items in the day or days before a ceremony. Eating a light, bland meal the evening before rather than consuming the brew on a completely empty stomach can also help, since some baseline nutrition reduces the shock to the digestive system. Ginger tea, taken 30 minutes before drinking, is a widely used remedy for plant-induced nausea.
What to Expect After Drinking
Effects from oral consumption typically begin around 1 to 2 hours after drinking, with peak effects arriving around the 2-hour mark. The total experience lasts 8 to 12 hours, which is longer than most other substances in the same class. This extended duration means preparation should include practical planning: clear your schedule for the full day, have water and light snacks available for afterward, and choose a comfortable, safe environment.
The initial period often involves the most physical discomfort, with nausea, mild sweating, and sometimes a sensation of heaviness. These symptoms usually subside as the experience intensifies. The long duration means effects taper gradually rather than ending abruptly, and most people feel noticeably tired the following day.