Psilocybin is the psychedelic compound found in psychedelic mushrooms and truffles. Upon entering the body, it is quickly metabolized into psilocin, which is responsible for psychedelic effects.
Psilocin acts on serotonin at the 5-HT2A receptor, increasing the amount of serotonin available in the brain, and producing profound changes in perception, such as visual and auditory hallucinations, tactile perceptions (such as tingling or warmth), and synaesthesia (the merging of senses).
Users of psilocybin report entering a profound state of mind where the usual limits of consciousness are expanded. Realizations about the self and the universe may come to the forefront, and people will often describe feelings of unity, interconnectedness, and unconditional love. Studies have shown that psilocybin can induce a mystical experience and that this positively correlates with the benefits that participants report following the psychedelic experience.