INCLUSION CRITERIA:
An individual who meets all of the following criteria will be eligible for study participation:
* Individuals between 18 and 65 years old
* Ability to understand and give informed consent.
* Current opioid use disorder (OUD) or OUD in remission while on maintenance therapy with OAT, as determined by DSM-5 with the M.I.N.I. interview (Mini-International Neuropsychiatric Interview).
* Current opioid agonist maintenance treatment in an opioid treatment program with methadone or buprenorphine for at least 14 days prior to study participation. With the following more specific criteria for each of these two medications:
* Current methadone maintenance treatment with a dose of ≥ 40mg/day, (maximum: 200mg/day), AND urinary toxicology positive for methadone and EDDP; OR
* Current buprenorphine maintenance treatment with a dose of ≥ 8mg/day (maximum: 24mg/day), AND urinary toxicology positive for buprenorphine.
EXCLUSION CRITERIA:
An individual who meets any of the following criteria will be excluded from participation:
* Participants who are non-English speaking.
* Psychiatric conditions under DSM-5 (examined with the MINI) that would make study participation unsafe or which would prevent adherence to study procedure; examples include: suicidal or homicidal ideation requiring immediate attention, inadequately-treated mental health disorder (e.g., active psychosis, uncontrolled bipolar disorder).
* Current diagnosis of a severe substance use disorder (except for opioid and nicotine/tobacco) in the past 3 months, based on the MINI interview, that would preclude safe participation in the study as determined by the study medical clinician.
* Alcohol intoxication when arriving at the study site (i.e., positive alcohol breathalyzer / alcohol salivary strips / urine alcohol).
* Signs of acute drug intoxication when arriving at the study site as determined by clinician assessment.
* Medical or psychiatric contraindications for CBD administration (e.g., history of hypersensitivity to cannabinoids); or any of the ingredients in the product (gelatin or sesame oil).
* Showing signs of acute opioid withdrawal symptoms (as determined by the result of the Clinical Opiate Withdrawal Scale (COWS). A Score of ≥ 5 or as interpreted by the investigator will be considered a positive result for withdrawal symptoms).
* Have a medical condition that would make study participation unsafe, which would make treatment compliance difficult, or would prevent adherence to study procedure. This includes, but is not limited to the following criteria:
* History of impaired renal function or elevated liver enzymes at prescreening. The exclusionary lab values are: \>4x the upper limit of normal (ULN) per laboratory criteria for AST or ALT, \>1.5x ULN for bilirubin or \<30mL/min/1.73m2 eGFR
* QTc Frederica \> 500ms
* Participating in another pharmacotherapeutic trial in the past 3 months.
* Participants who have used any medication, dietary supplements (and/or grapefruit juice), or combination of medications and supplements known to alter the metabolism of, or interact with CBD (buproprion, rifampin, barbiturates, phenothiazines, cimetidine, etc.) 14 days prior to and during the duration of the study
* For women: being pregnant (positive urine test for pregnancy) or breastfeeding.
* Not using an appropriate method of contraception such as hormonal contraception (oral hormonal contraceptives, Depo-Provera, Nuva-Ring), intrauterine device (IUD), sterilization, or double barrier method (combination of any two barrier methods used simultaneously, i.e. condom, spermicide, diaphragm).
* Participants who have been court mandated to attend treatment centers.
