Does marijuana legalization reduce opioid abuse? Evidence is mixed. | Research

The takeaway

Eight of ten studies found associations between marijuana decriminalization and reduced opioid use, but one cohort study found increased adverse opioid outcomes, and the overall evidence is limited by ecological study designs.

Policymakers, pain management clinicians, and public health researchers.

8 of 10 studies found reduced opioid use in legal states

What the researchers found

Of 10 studies meeting inclusion criteria (3 cross-sectional, 6 ecological, 1 retrospective cohort), 8 found associations between marijuana decriminalization policies and reduced prescription opioid use. One study was inconclusive, and the retrospective cohort study reported an increase in adverse opioid-related outcomes. The ecological designs use aggregate data and cannot establish that the same individuals used cannabis instead of opioids.

Why it matters

The opioid crisis has driven interest in cannabis as a potential substitute for opioid pain management. Understanding whether this population-level relationship holds is critical for policy decisions.

The numbers in context

10 studies met inclusion criteria. 8 found association between marijuana policies and reduced opioid use. 1 inconclusive. 1 found increased adverse outcomes. Study types: 3 cross-sectional, 6 ecological, 1 retrospective cohort.

How the study worked

Clinical inquiry (Clin-IQ) searching Ovid MEDLINE, MEDLINE In-Process, and Embase for population-based studies from January 2012 through December 2018 examining the relationship between marijuana decriminalization and opioid-related outcomes.

What this study cannot tell us

Mostly ecological studies using aggregate data. Cannot determine individual substitution behavior. Confounded by other policy changes occurring simultaneously. Search limited to one database family.

How to read the evidence

Systematic search with clear criteria, but underlying studies are mostly ecological with inherent limitations.

When this study was published

2019 review of studies from 2012-2018.

The bigger picture

The one cohort study that tracked individuals (rather than aggregate state-level data) found the opposite result, which highlights the danger of making individual-level conclusions from state-level data.

Questions still open

Does individual-level cannabis substitution for opioids occur, or are the ecological associations driven by other factors? Do specific cannabis access policies (dispensary proximity, product types) matter more than legalization status?

Common questions

Does legalizing marijuana reduce opioid use?

Eight of ten studies found associations between marijuana legalization and reduced opioid use at the population level, but most used aggregate state data rather than tracking individuals. The one study that tracked individuals found the opposite result.

Can cannabis replace opioids for pain?

Population-level data suggest an association between cannabis access and lower opioid use, but whether individuals are actually substituting cannabis for opioids remains unclear from the available evidence.

Read the original research

Is There Less Opioid Abuse in States Where Marijuana Has Been Decriminalized, Either for Medicinal or Recreational Use? A Clin-IQ.

Journal of patient-centered research and reviews, 6(4), 267-273

View on PubMed ↗Publisher’s paper ↗

Citation

Wendelboe, Aaron M; Mathew, Richard; Chongsuwat, Tana; Rainwater, Elizabeth; Wendelboe, Mark A; Wickersham, Elizabeth; Chou, Ann F. (2019). Is There Less Opioid Abuse in States Where Marijuana Has Been Decriminalized, Either for Medicinal or Recreational Use? A Clin-IQ.. Journal of patient-centered research and reviews, 6(4), 267-273. https://doi.org/10.17294/2330-0698.1704