Fig. 1. Acute subjective effects on the Visual Analog Scale (VAS) and plasma concentrations over time that were induced by mescaline (300 and 500 mg), LSD, psilocybin, and placebo.

The 500 mg mescaline dose, LSD, and psilocybin induced similar subjective peak effects on all items. The low 300 mg mescaline dose induced lower peak effects than the high 500 mg mescaline dose, LSD, and psilocybin. The substances differed in their durations of action. Mescaline showed the longest effect duration of action compared with the other substances, followed by LSD and lastly psilocybin. The onset rates of subjective effects of LSD and psilocybin were comparable, whereas mescaline showed a slower onset and delayed peak of subjective effects. The substances were administered at t = 0 h. The data are expressed as the mean ± SEM ratings in 32 participants for LSD and psilocybin and in 16 participants for each mescaline dose. The corresponding statistics are presented in Supplementary Table S1.