Psilocybin Therapy for Methamphetamine Use Disorder and HIV

Inclusion Criteria: * Age 25 to 64 * Diagnosed with HIV at least 3 months ago * Moderate-to-severe methamphetamine use disorder * Uses methamphetamine regularly and identifies it as their primary drug * Has a goal of quitting methamphetamine use * Able and willing to abstain from methamphetamine and other non-prescribed drugs for at least 24 hours prior to and throughout psilocybin dosing sessions * Currently living indoors with stable housing anticipated for the duration of the study * Has a text-capable cellphone * Willing to use highly effective contraception and not donate sperm throughout the study * Able to participate in study procedures in English Exclusion Criteria: * History of any primary psychotic disorder (e.g., schizophrenia or schizoaffective disorder), bipolar I disorder, or certain other psychiatric conditions as determined by study assessment * Current moderate-to-severe opioid, alcohol, or sedative use disorder (Note: people on stable doses of buprenorphine or methadone may be eligible) * Currently taking certain medications that may interact with psilocybin * Recent use of a psychedelic drug * Certain significant heart, liver, or kidney conditions * Uncontrolled high blood presure (i.e., \>150/90 mmHg) * History of stroke or seizure in the past year * Current pregnancy or breastfeeding * Current involvement in the criminal legal system that would be expected to interfere with study participation * Current or planned enrollment in a contingency management program or another investigational substance use treatment trial within the past month Note: Additional eligibility criteria apply. Certain criteria and thresholds are not listed here to preserve the scientific integrity of the study.