Inclusion Criteria:
* 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 with methadone or buprenorphine for at least 14 days prior to consent. With the following more specific criteria for each of these two medications:
* Current methadone maintenance treatment with a dose of ≥ 10mg/day, (maximum: 250mg/day), AND urinary toxicology positive for methadone and 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP).
* Current buprenorphine maintenance treatment with a dose of ≥ 2mg/day (maximum: 32mg/day), AND urinary toxicology positive for buprenorphine.
Exclusion Criteria:
* 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 (i.e. high risk for suicide on the Columbia suicide severity rating scale (C-SSRS) screen version) 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.
* 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: • \< 30mL/min/1.73m2 eGFR. •QTc Fridericia \> 500ms at screening. •Elevated liver enzymes at screening. The exclusionary lab values are: \>4x the upper limit of normal (ULN) per laboratory criteria for AST or ALT or \>1.5x ULN for bilirubin.
* Participating in another pharmacotherapeutic trial in the past 3 months.
* Participants who have used (within 14 days prior to consent) or plan to use (during the 24-week treatment period) any medications, 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, anticoagulants, antiplatelets, etc.).
* 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
