Clinical trials

The goal of this clinical trial is to learn whether it is possible to use psilocybin in combination with motivational support therapy to treat moderate-to-severe methamphetamine use disorder (MeUD) in people with HIV who are seeking to stop using methamphetamine. The main questions it aims to answer are: * Do people with HIV and MeUD find psilocybin with motivational support therapy feasible and acceptable as a potential treatment? * Is psilocybin safe and tolerable among people with HIV and MeUD? Participants will: * Be randomly assigned to receive a single monitored dose of either 25 mg (higher dose) or 5 mg (lower dose) psilocybin * Have 3 preparation and 3 integration motivational support therapy visits before and after the psilocybin dosing session. * Report their methamphetamine use prior to, during, and up to 3 months following the intervention * Optionally receive one additional open-label 25 mg psilocybin session after the 4-week assessment, if eligible