Psilocin (also known as 4-HO-DMT, 4-hydroxy DMT, psilocine, psilocyn, or psilotsin) is a substituted tryptamine alkaloid and a serotonergic psychedelic substance. It is present in most psychedelic mushrooms together with its phosphorylated counterpart psilocybin. Psilocin is a Schedule I drug under the Convention on Psychotropic Substances and is a Schedule 1 controlled drug under he Misuse of Drugs Regulations 2017.
Under SI 237/2023 Misuse of Drugs Act 1977 (Controlled Drugs) (Designation) (Amendment) Order 2023 possession of a Schedule 1 controlled drug is permitted for research, forensic analysis or use as an essential intermediate or starting material in an industrial manufacturing process; this may include clinical trials. Consequently there is no requirement to consider rescheduling of psilocyn for medical research purposes.