The Association Between Cannabis Legalization and Opioid Overdoses

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In the United States, the opioid epidemic has been an ongoing crisis taking place over the past two-plus decades that continues to present a significant challenge. As reports have indicated, in 2021, there were a record-setting number of fatal overdoses, more than any previous year.

As a result, these data have encouraged state governments to find ways to begin reversing the scourge of opioid addiction and death by passing legislation that legalizes cannabis for medical or recreational use. In fact, a cohort study published in JAMA Health Forum set out to investigate whether there is any sort of correlation between these new recreational cannabis laws and a possible reduction in synthetic opioid deaths.¹

When it comes to the treatment of acute or chronic pain, history has shown that it is, in fact, possible for people to substitute synthetic opioids as a treatment method with cannabis; conversely, the opposite also holds true, as some have argued that cannabis is actually a gateway drug. Empirical research conducted in the past has presented varied results in this space, given the fact that existing literature has several limitations, according to the authors of the current study. For example, with many studies using traditional difference-indifferences (DD) analyses to determine the impact of legalization, the authors noted that these estimates could potentially be invalid, due to policies varying across state lines; the investigators also note that there does not appear to be any study that has been able to account for any biases based off of assessing medical and recreational cannabis law simultaneously.

The current study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guidelines, while using state-level aggregate data that are all available to the public. To help properly address the research-based challenges, the authors used a generalized DD design created by de Chaisemartin and d’Haultfoeuillethat is able to test the connection between state cannabis laws and opioid-related outcomes. The authors are clear in stating that “like other methods, this method involves comparing outcome changes in treated states (states that implemented the law) with changes in outcomes in control states, but it carefully defines and selects valid control states for these comparisons.”

A state was only considered treated in a period if it had cannabis dispensaries operating during that specific timeframe. The study chose the period of January 2006-December 2020, utilizing various sources for data from the US Centers for Disease Control and Prevention (CDC), along with IQVIA’s Xponent database that provides opioid prescription rates consisting of data from more than 50,000 retail pharmacies, a number that features over 90% of total retail prescriptions in the country.

Overall, the changes in prescribed opioids associated with implementation of recreational cannabis law were not statistically significant. There was an average of 3.08 fewer prescriptions per 100 people (P = 0.17), and a 95% confidence interval that ranged from a decrease of 7.43 prescriptions (a 10% decrease compared with the yearly average of 73.4 prescriptions across all states during the timeframe) to an increase of 1.27 prescriptions (a 2% increase).

Due to these numbers, the authors concluded that, “In our analyses accounting for the staggered implementation of cannabis laws in a dynamic clinical and policy environment, we found no evidence that the implementation of recreational or medical cannabis laws was associated with opioid prescriptions or opioid mortality, with the exception of a possible reduction in synthetic opioid deaths associated with recreational cannabis law implementation.”

Reference

1. Nguyen HV, McGinty EE, Mital S, Alexander GC. Recreational and Medical Cannabis Legalization and Opioid Prescriptions and Mortality. JAMA Health Forum. 2024;5(1):e234897. doi:10.1001/jamahealthforum.2023.4897