Cannabidiol in Opioid Use Disorder and Chronic Pain

Inclusion Criteria: * Males and females, Veterans and non-Veterans, aged between 18 and 70 years old. * Diagnosed with OUD and currently enrolled in methadone or buprenorphine maintenance treatment. * Having chronic pain, uniformly operationalized as grade II (high-intensity) non-cancer pain for ≥ 6 months. * Capable of providing informed consent in English. * Compliant in opioid maintenance treatment and on a stable dose for four weeks or longer. * Not meeting DSM-5 criteria for substance use disorders other than OUD or tobacco use disorder within the last 12 months. * No current medical problems deemed contraindicated for participation by principal investigator. * For women, not pregnant as determined by pregnancy screening; not breast-feeding; using acceptable birth control methods. Acceptable contraception for females includes oral contraceptives, contraceptive depot injections, contraceptive subdermal implants, intrauterine devices, or surgical contraception methods. Acceptable contraception for males includes condoms or surgical contraception methods. Exclusion Criteria: * Other current major psychiatric disorders deemed clinically unstable by the principal investigator, such as severe depression and/or active suicidal ideation. * Having experienced major psychosocial stressors recently (≤ 6 weeks before enrollment), at the discretion of the principal investigator. * Methadone dose under 30 mg or over 150 mg/day. * Buprenorphine dose over 24 mg per day. * Having rece…