ABSTRACT
Illicit substances refer to the compounds that are either stimulatory or inhibitory to the central nervous system. These compounds cause hallucinogenic effects, hence, their use has been forbidden. This chapter emphasises the psychoactive illicit substances of fungal origin. Psilocybin is present in hallucinogenic mushrooms which are also called ‘magic mushrooms’. It discusses the neurological and related adverse events associated with pharmacokinetic interactions between illicit substances of fungal origin and clinical drugs in humans. The chapter also highlights insights into the future studies to further understand the underlying pharmacokinetic mechanisms of adverse neurological and related adverse events. Psilocybin is found in certain mushrooms, such as those from genus Conocybe, Gymnopilus, Panaeolus, Pluteus, and Psilocybe.
