Evaluating Tetrahydrocannabinol as an Adjunct to Opioid Agonist Therapy

This is a single‐site, two‐phase pilot clinical trial evaluating the safety and feasibility of administering a balanced 1:1 ratio of THC:CBD cannabis oil alongside methadone‐based opioid agonist therapy (OAT) in a community setting. Phase 1 is a 12‐week, double‐blind, randomized controlled study involving 24 eligible participants with opioid use disorder (OUD) who recently initiated or re‐initiated methadone‐based OAT. Participants will be randomly assigned to receive either balanced THC:CBD cannabis oil or placebo oil. All participants will receive OUD clinical care, including OAT management, independent of research visits. After the 12‐week blinded treatment period (Phase 1), eligible participants will be invited to Phase 2, a 12‐week open‐label treatment extension study with all participants receiving balanced THC:CBD cannabis oil. Follow‐up research visits will occur every two weeks from the start of open‐label treatment.