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Relationship Between Medical Cannabis Legalization and Opioid-Related Mortality Rates



  • The use of medical cannabis has been shown to offer therapeutic effects to combat patients with opioid use disorder, including decreased ratings of chronic pain and withdrawal.

  • Various studies have explored the effect of medical cannabis on rates of opioid overdose deaths; however, the conclusions have thus far been inconsistent.

  • The effect of medical cannabis legalization needs to be better examined to determine its effect on opioid-related deaths.


The opioid epidemic has become one of the most extensive public health crises in the United States and Canada. Those with opioid use disorder (OUD) are at high risk of overdose deaths, with over 100,000 opioid-related overdose deaths in 2021 (1). This epidemic has been complicated by the introduction of the illicitly manufactured synthetic opioid, fentanyl, which was involved in almost all accidental opioid overdose deaths in 2018 in Canada (2). Opioid medications are commonly used to manage chronic non-cancer pain; however, their propensity to be abused is high. To combat the high rates of opioid overdose deaths, medical cannabis has been studied both to manage chronic non-cancer pain as well as to reduce the rates of accidental overdoses due to opioids. The goal of this analysis is to explore the effect of the use of medical cannabis on rates of opioid overdoses.

Cannabis that is high in its naturally occurring cannabidiol (CBD) and low in tetrahydrocannabinol (THC) may have a role as an alternative to opioids in managing chronic pain (3). In a study with 21 patients with chronic pain, pain ratings were reduced by 27% after inhalation of vaporized cannabis three times daily (4). Additionally, there have been no documented cases of cannabis overdose deaths, which can speak to the safety profile of using cannabis as a substitute for opioids for pain management (2). However, there is still much to learn about the utilization of cannabis from a medical perspective. Some factors needing further investigation include respiratory issues with inhalation of cannabis, its psychoactive effects in specific patient populations, and a more comprehensive safety profile of cannabis use.

Under the Controlled Substance Act (CSA) of 1970, cannabis was given the designation of being a Schedule I drug. This classified cannabis as having a high potential for abuse and addiction, with no accepted medical use (5). However, in recent years, the use of medical cannabis has been seen as a potentially effective harm reduction strategy to reduce opioid use and related morbidity and mortality rates (6). Cannabis use was longitudinally associated with a reduced likelihood of recent exposure to fentanyl, which may have correlated effects on overdose death rates (7). One study looking at data from the Centers of Disease Control (CDC) with US census data in 812 counties throughout 23 states determined that “an increase from one to two storefront dispensaries in a county is associated with an estimated 17% reduction in all opioid-related mortality rates” (8). This study established that higher numbers of medical and recreational cannabis dispensaries are associated with lower rates of overdose deaths, particularly with those involving fentanyl (8). On a broader scale, “states with medical cannabis laws had a 24.8% lower mean annual opioid overdose mortality rate” compared with states without medical cannabis laws (9). This trend is reinforced with time – researchers determined that medical cannabis laws were associated with lower rates of opioid-related deaths that strengthened in the years after the passage of these laws (9). These findings indicate that other studies may need to be explored longitudinally to determine trends between medical cannabis legalization and opioid-related deaths.

Despite multiple studies noting the association between the use of medical cannabis for chronic pain and a decrease in opioid overdose deaths, a study published in 2021 challenged these findings, stating that, medical cannabis laws had the opposite effect on opioid overdose deaths (10). Specifically, the study found that between 2012 and 2017, opioid overdose deaths were higher in states that allowed medical cannabis use. Additionally, the study found that “ the association between state medical cannabis laws and opioid overdose mortality reversed direction from −21% to +23% and remained positive after accounting for recreational cannabis laws”. However, these results may have been confounded due to their finding that states without medical cannabis laws had “lower overdose reporting quality” (10).

A meta-analysis investigating 16 related studies on medical cannabis and associated opioid use and adverse effects found that states with legalized medical cannabis had a non-significant reduction in both opioids dispensed and opioid overdose mortality, 7% and 8% respectively (11). Though the statistics show that the decreased opioid mortality rate was insignificant, there does seem to be a trend in decreased opioid prescriptions and state-specific mortality rates. This systemic review also cited another study that established that recreational use of marijuana was associated with a statistically significant 7% reduction in opioid overdose mortality in Colorado and a 6% reduction in opioid prescriptions (11,12). These collective findings may signal a promising start to the use of medical cannabis as a therapeutic solution to the opioid crisis nationwide.

It is overall difficult to come to a consensus as to the effects of cannabis on opioid-overdose mortality as well as other opioid-related health outcomes. Future studies need to further examine the role of medical cannabis in opioid overdose mortality rates on a broader population.


  1. U.S. overdose deaths in 2021 increased half as much as in 2020 - but are still up 15%. Centers for Disease Control and Prevention. Published May 11, 2022. Accessed July 18, 2022.

  2. Carter GT, Flanagan AM, Earleywine M, Abrams DI, Aggarwal SK, Grinspoon L. Cannabis in palliative medicine: Improving care and reducing opioid-related morbidity. American Journal of Hospice and Palliative Medicine®. 2011;28(5):297-303. doi:10.1177/1049909111402318.

  3. Lucas P. Rationale for cannabis-based interventions in the opioid overdose crisis. Harm Reduction Journal. 2017;14(1). doi:10.1186/s12954-017-0183-9.

  4. Abrams DI, Couey P, Shade SB, Kelly ME, Benowitz NL. Cannabinoid–opioid interaction in chronic pain. Clinical Pharmacology & Therapeutics. 2011;90(6):844-851. doi:10.1038/clpt.2011.188.

  5. Drug scheduling. DEA. Accessed June 21, 2022.

  6. Collen M. Prescribing cannabis for harm reduction. Harm Reduction Journal. 2012;9(1):1. doi:10.1186/1477-7517-9-1.

  7. Socías ME, Choi JC, Lake S, et al. Cannabis use is associated with reduced risk of exposure to fentanyl among people on opioid agonist therapy during a community-wide overdose crisis. Drug and Alcohol Dependence. 2021;219:108420. doi:10.1016/j.drugalcdep.2020.108420.

  8. Hsu G, Kovács B. Association between county level cannabis dispensary counts and opioid related mortality rates in the United States: Panel Data Study. BMJ. 2021:m4957. doi:10.1136/bmj.m4957.

  9. Bachhuber MA, Saloner B, Cunningham CO, Barry CL. Medical cannabis laws and opioid analgesic overdose mortality in the United States, 1999-2010. JAMA Internal Medicine. 2014;174(10):1668. doi:10.1001/jamainternmed.2014.4005.

  10. Shover CL, Davis CS, Gordon SC, Humphreys K. Association between medical cannabis laws and opioid overdose mortality has reversed over time. Proceedings of the National Academy of Sciences. 2019;116(26):12624-12626. doi:10.1073/pnas.1903434116.

  11. Chihuri S, Li G. State marijuana laws and opioid overdose mortality. Injury Epidemiology. 2019;6(1). doi:10.1186/s40621-019-0213-z.

  12. Livingston MD, Barnett TE, Delcher C, Wagenaar AC. Recreational cannabis legalization and opioid-related deaths in Colorado, 2000–2015. American Journal of Public Health. 2017;107(11):1827-1829. doi:10.2105/ajph.2017.304059.

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