• Cannabis use disorder: Limited. In a 2019 trial of 128 people, a THC/CBD mouth spray plus counseling cut illicit cannabis use to 35 days versus 53 on placebo over 12 weeks (Lintzeris 2019 summary). A 2026 review found THC/CBD combinations reduced withdrawal and use.
• Opioid use disorder: Not established. The 2026 review found no benefit, and the state clinical guideline finds the evidence insufficient. One small trial found CBD reduced craving (see Opioids).
• Alcohol, cocaine, and tobacco: Not established.

Compared with standard treatment: Buprenorphine and methadone are the standard of care for opioid use disorder and reduce overdose deaths. Counseling is first-line for cannabis use disorder.

Good to know: Cannabis is not a substitute for buprenorphine or methadone; never stop them on your own. A history of substance use disorder is a reason for extra caution with medical cannabis.

What to ask for: Cannabis should be used for a substance use disorder only as part of a supervised plan with an addiction specialist.