Systematically Testing the Evidence on Marijuana

Cannabis and Medications for Opioid Use Disorder

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Cannabis and Medications for Opioid Use Disorder

By: Honora Englander MD, Avery Richardson BS, and Emily Skogrand PharmD

Background

The medications methadone and buprenorphine are effective treatments for opioid use disorder (OUD), with decades of evidence supporting their use to improve health outcomes and reduce overdose and all-cause mortality.1 Cannabis use among people treated with medications for OUD (MOUD) is common, but clinical practices and policies related to cannabis use and MOUD vary: clinicians may reduce MOUD doses, increase MOUD monitoring, or otherwise limit MOUD access because of concurrent cannabis use.2,3 This brief summarizes evidence about the effects of cannabis use among people on MOUD, describes pharmacologic interactions between cannabis and MOUD, and discusses policy and practice implications given the current state of the evidence.

Medications for OUD are effective, but access is limited, and treatment discontinuation is associated with poor outcomes. Methadone and buprenorphine, plus extended-release naltrexone, are the three FDA-approved medications for OUD in the US. Decades of evidence show that methadone and buprenorphine treat withdrawal and cravings, reduce substance use, reduce risk of infection and other drug-related harms, and reduce risk for overdose and death.1 While typically not first-line recommended therapy, extended-release naltrexone is an alternative for motivated patients who are able to tolerate induction onto an opioid antagonist medication.4

Despite their effectiveness, patients commonly struggle to access MOUD; fewer than 1 in 5 people who could benefit receive them.5,6 Moreover, discontinuing MOUD is associated with markedly increased risk of death.7

Cannabis use among patients on MOUD or attempting to access MOUD is common.8 Treating clinicians may recognize cannabis use in patients taking MOUD if discovered incidentally on urine drug test, when patients ask about cannabis use (for example, by requesting a medical cannabis card), or because of policies at certain treatment centers that forbid cannabis use. This is important because in some centers, cannabis use could be a barrier to MOUD access or MOUD continuation, which in turn has important implications for patient health and mortality.

Pharmacologic interactions between cannabis and MOUD

Data on drug-drug interactions between the principal components of cannabis (Tetrahydrocannabinol [THC] and cannabidiol [CBD]) and MOUD are limited and are extrapolated from prescription formulations of THC and CBD and from small case reports. THC has no known interactions with any MOUD (methadone, buprenorphine, or naltrexone) or prescription opioids. THC could theoretically increase buprenorphine levels through inhibition of CYP3A4; however, outside of a single small case series10 this has not been described, and there is no evidence suggesting a need to adjust buprenorphine doses in people consuming THC. CBD could potentially interact with methadone via inhibition of enzymes involved in methadone metabolism (2C19, 3A4 and 2C9), which could lead to changes in serum methadone levels (e.g., an acute decrease in CBD could reduce methadone levels). However, outside of a single-patient case report, no studies describe clinically significant interactions between CBD and methadone. Clinically significant interactions between CBD and buprenorphine are unlikely. There are no shared metabolic pathways between naltrexone and CBD.

Clinical studies exploring the effects of cannabis use on health outcomes among people taking MOUD

  • Does cannabis use change risk of non-medical opioid use among people on MOUD?

No. A 2024 systematic review and meta-analysis explored the impact of cannabis use on the risk of non-medical opioid use among people receiving MOUD.11 Authors identified 10 studies that met their inclusion criteria. Studies included 8,367 participants (38% female), the average follow-up time was 9.7 months (range 4-15 months) and included patients who were prescribed methadone (76.3%), buprenorphine (21.3%), and naltrexone (2.4%). Pooled results found no significant association between cannabis use and non-medical opioid use. As the authors summarize: “These findings neither confirm concerns about cannabis increasing non-medical opioid use during MOUD, nor do they endorse its efficacy in decreasing non-medical opioid use with MOUD. This indicates a need for individualized approaches for cannabis use and challenges the requirement of cannabis abstinence to maintain OUD pharmacotherapies.”11

  •  Does cannabis improve opioid cravings or withdrawal among people on MOUD?

Preliminary evidence suggests most likely not. Methadone and buprenorphine—when provided at clinically appropriate doses—reduce opioid withdrawal and cravings, however some research explores whether cannabis may further improve these symptoms if they persist and/or for people on subtherapeutic doses of MOUD. A secondary analysis of a multi-center, pragmatic randomized controlled trial in individuals with prescription-type OUD randomized to either buprenorphine or methadone found no effect of cannabis use on cravings or withdrawal.12 Another small observational study of patients on subtherapeutic methadone doses found that cannabis may mitigate some of the negative effects of subtherapeutic methadone dosing,13 however this effect did not translate to time retained in methadone treatment.14

  •  Should co-occurring cannabis use lead clinicians to discontinue, reduce doses, or restrict access to MOUD?

 No. Cannabis is associated with significantly less harm than unregulated opioids such as heroin or fentanyl, both when considering harms to people who use drugs and harms to others.9 Despite this, many clinicians and/or clinic policies require that patients are completely abstinent from all drugs, including cannabis, to be eligible to receive methadone and/or buprenorphine. These practices and policies are neither evidence-based nor supported by expert recommendations. MOUD does not address cannabis cravings or cannabis use, and evidence does not support increased harms of MOUD based on cannabis use alone.11 Moreover, expert guidance recommends against requiring abstinence from any—let alone all—substances as a condition of treatment, suggesting that it is “unnecessary and ultimately restricts our ability to prevent serious harms, including overdose deaths, and improve public health.”15 Discontinuing MOUD because of concurrent cannabis use may also discourage patients from disclosing use and could lead to missed opportunities to discuss and counsel patients about health effects of cannabis use. No studies support benefits of limiting access to methadone take-home doses or otherwise restricting access to MOUD because of concurrent cannabis use. Cannabis consumption alone should not result in MOUD dose reductions or heightened monitoring (such as more frequent visits, restricted access to methadone take-home doses, or additional urine drug testing). 

  • Should clinicians support policies or practice that promote replacing MOUD with cannabis?

No. Some states have made OUD a qualifying condition for medical cannabis. These policies are unsupported by evidence and may lead to harm. Notably, cannabis dispensaries in states where OUD is a qualifying condition for medical cannabis are more likely to promote misinformation, including that cannabis is an effective treatment for OUD and that cannabis can replace FDA-approved MOUD.16 Clinicians should know if their state designates OUD as a qualifying condition for medical cannabis,17 offer patients accurate information about evidence-based MOUD, and discuss potential harms of misinformation related to cannabis and MOUD with patients. 

  • What should clinicians do for patients taking MOUD who consume cannabis?

Clinicians should explore patient perceptions of cannabis use—including benefits and harms18—and screen for cannabis use disorder. Optimally, clinical decision making prioritizes retention in MOUD and engagement in healthcare,19 recognizing that risks and benefits may vary based on patient population (for example, among adolescents20 or in pregnancy21).

Future research

Future research could explore patient perceptions of benefits and harms related to cannabis while taking MOUD. Such information could guide clinicians to better counsel patients and inform additional research to better understand the relationship between cannabis and MOUD.

Bottom Line

  • MOUD is a life-saving treatment for patients with OUD, but few people access it, and treatment retention is a problem. It is important to remove barriers to MOUD use.
  • Clinicians and policies should not reduce, restrict, or stop MOUD for cannabis use.
  • Clinicians should explore individual patient perceptions of benefits and harms of cannabis use while taking MOUD.
  • Clinicians should know state cannabis policies and address potential sources of misinformation that might deter patients from taking MOUD.

 

Suggested citation: Englander H, Richardson A, Skogrand E. Cannabis and medications for opioid use disorder. The Systematically Testing the Evidence on Marijuana Project; April 2025. Accessed (Month DD, YYYY). https://www.cannabisevidence.org/clinician-resources/clinician-briefs/cannabis-and-MOUD

Author Affiliations: All authors are affiliated with Oregon Health & Science University.

Acknowledgements: Thank you to Michael Incze MD, MSEd and Brian Chan MD for critically reviewing this document. 

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References

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Page Last Reviewed:  May 2025