Recreational Cannabis Laws Initially Reduced Opioid Misuse, but the Effect Faded After 2-3 Years | Research

The takeaway

Analysis of national survey data found recreational marijuana laws initially reduced frequent prescription opioid misuse, but the effect dissipated after only 2-3 years when using methods that account for staggered state adoption.

Policymakers interested in cannabis legalization as an opioid crisis strategy

Effect fades after 2-3 years

What the researchers found

Standard difference-in-differences analysis suggested RML adoption reduced frequent opioid misuse. However, a two-stage procedure accounting for staggered treatment timing showed the opposite direction. Event study estimates suggested an initial decrease in opioid misuse that dissipated after 2-3 years, indicating the benefit was temporary.

Why it matters

The finding that the opioid substitution effect of cannabis is temporary challenges the hopeful narrative that cannabis legalization can durably reduce the opioid crisis. Initial benefits may fade as novelty wears off or as people return to prior patterns.

The numbers in context

Standard DD showed reduced opioid misuse; two-stage procedure showed the DD estimate became positive; event study showed initial decrease dissipating after 2-3 years

How the study worked

Analysis of National Survey on Drug Use and Health microdata examining recreational marijuana laws and prescription opioid misuse (OxyContin, Percocet, Vicodin). Used both standard difference-in-differences regression and a two-stage procedure designed for staggered treatment adoption and dynamic effects.

What this study cannot tell us

Observational study cannot prove causation. Different statistical methods produced different results, introducing uncertainty. Self-reported substance use data may underestimate misuse. Staggered legalization across states complicates temporal comparisons.

How to read the evidence

Rigorous econometric analysis of national survey data with multiple methods, though different approaches yielded different results

When this study was published

2023 study

The bigger picture

Previous research celebrating opioid reductions from cannabis legalization may have been premature. If the substitution effect is temporary, relying on cannabis legalization as an opioid crisis strategy without sustained complementary interventions may not work long-term.

Questions still open

Why does the opioid reduction effect dissipate? Could sustained public health campaigns maintain the substitution effect? Does the temporary reduction reflect initial curiosity about cannabis as a pain alternative that fades?

Common questions

Does cannabis legalization reduce opioid use?

Initially, yes. This study found recreational marijuana laws were associated with reduced opioid misuse, but the effect disappeared after 2-3 years, suggesting the benefit is temporary.

Why did different statistical methods produce different results?

Standard methods treat all state legalizations as simultaneous, which can bias results when states legalize at different times. More sophisticated methods accounting for staggered adoption showed the reduction was short-lived.

Read the original research

Recreational marijuana laws and the misuse of prescription opioids: Evidence from National Survey on Drug Use and Health microdata.

Health economics, 32(2), 277-301

View on PubMed ↗Publisher’s paper ↗

Citation

Ali, Mir M; McClellan, Chandler; Mutter, Ryan; Rees, Daniel I. (2023). Recreational marijuana laws and the misuse of prescription opioids: Evidence from National Survey on Drug Use and Health microdata.. Health economics, 32(2), 277-301. https://doi.org/10.1002/hec.4620