An unfortunate reality of taking natural psychedelics is that they can vary widely in potency and result in either unexpectedly heavy or disappointingly light trips. San Pedro and Peruvian Torch in particular can contain anywhere from 0-3% mescaline by weight, making them hard to dose properly.

Whether you’re using powdered cactus “incense” or preparing a cutting you grew yourself for consumption, it’s a good idea to determine how strong it is by taking a low dose and slowly increasing it until you feel effects. Getting an idea of how strong or weak it is will help you whether you want to microdose, or plan for a heavy trip.

A threshold dose of pure mescaline is about 50 milligrams. This is where most people experience effects like light euphoria or tingly physical sensations. If the cactus you have is strong, you might feel something at 2-4 grams. It’s a good idea to start with 2; in the worst case, you’ll get a microdose and still have some subtle benefits. If you don’t feel anything, try 4-6 grams a few days later; if you still don’t feel it, move up to 7-8 grams next time.

If you are lucky enough to feel something at 2 grams, the powder you have probably is near the 3% end of the spectrum. This is rare, but still within the range of possibilities. Even if it’s good, San Pedro is more likely to have around 2% mescaline, along with some other psychoactive alkaloids that contribute to the experience. At 2%, you might expect to feel something from a 4-6 gram dose.

Peruvian Torch is more consistent with mescaline content, but generally has a bit less, around 0.5-1% by weight. You might need anywhere from 8-12 grams to feel something in this range, but it’s still a good harm reduction practice to start much lower and work your way up unless you’re okay with the unpredictable possibilities.