Altered States of Consciousness During Ceremonial San Pedro Use

San Pedro, a mescaline containing cactus, has been used for thousands of years and is currently popular as a psychedelic substance in ceremonial retreats in Europe. The current research investigates the consciousness altering effects of San Pedro. Forty-two participants who joined ceremonial psychedelic retreats in the Netherlands were investigated with questionnaires probing 11 dimensions of altered states of consciousness (11D-ASC), ego-dissolution, mystical experiences, and challenging experiences. Results tentatively demonstrate the status of San Pedro as a psychedelic, revealing deviations from normal waking consciousness on all 11 subscales of the 11D-ASC, moderate scores of ego-dissolution, and a complete mystical experience in two thirds of the participants. Furthermore, a consciousness profile of San Pedro was constructed, which revealed that spiritual experiences are strongly expressed in ceremonial San Pedro use. Furthermore, the San Pedro experience is characterized by low levels of disembodiment, anxiety, impaired control and cognition, transcendence of space, and relatively higher levels of physical distress and grief in case of (incidental) challenging experiences. Finally, graph network analysis indicated two separate networks of positive and negative altered states of consciousness. Possible interpretations of these findings are discussed in relation to the ceremonial setting, sympathomimetic effects of San Pedro's alkaloids and variations in affective valence.