San Pedro Cactus, Trichocereus pachanoi has a long history of ritual use in oracles, sexual magic, out-of-body-flights and shamanism in pre-Hispanic times. Today Peruvian curanderos still ingest San Pedro Cactus during their nocturnal mesa rituals. San Pedro Cactus is used primarily by shamans in psychedelic rituals. In Peruvian folk medicine preparations of San Pedro Cactus are used as a aphrodisiac and tonics.

San Pedro Cactus should be dried after the ribs are cut apart and the skin or rind is cut away at the place were the green coloration of the flesh disappears. Then San Pedro Cactus is placed in the sun and once the skin starts to roll up it should be flipped over, drying San Pedro Cactus can take from two to six days.

Dried San Pedro Cactus should be ground to a fine powder, the more finely ground San Pedro Cactus is the better absorption of the mescaline. Dried San Pedro Cactus can be gel-capped as the taste of dried San Pedro Cactus can be very bitter. Dried San Pedro Cactus can be dissolved into a juice, water, tea or some other liquid but must be consumed as quickly as possible otherwise it will congeal into a mass. 

According to Jim DeKorne who wrote Psychedelic Shamanism he estimates that 100 grams of dried San Pedro Cactus will yield 300 milligrams of pure mescaline.