Cannabis Use Linked to Less Fentanyl Exposure in Opioid Treatment Patients | Research

The takeaway

Among 819 people on opioid agonist therapy in Vancouver, those who used cannabis were 9% less likely to test positive for fentanyl on urine drug testing.

Addiction medicine specialists, harm reduction advocates, opioid crisis researchers

Cannabis use was associated with 9% reduced fentanyl exposure among OAT patients

What the researchers found

In a prospective cohort of 819 participants on opioid agonist therapy (OAT) contributing 1,989 observations (2016-2018), cannabis use (detected by urine testing) was independently associated with a 9% reduced likelihood of fentanyl exposure (adjusted prevalence ratio=0.91, 95% CI: 0.83-0.99).

Why it matters

During the ongoing opioid overdose crisis driven by illicitly manufactured fentanyl, any intervention that reduces fentanyl exposure among high-risk individuals could save lives. This study suggests cannabis may play a harm-reduction role for people on OAT.

The numbers in context

819 participants on OAT; 1,989 observations; fentanyl detected in 53% at baseline; cannabis users had lower fentanyl prevalence (47% vs 56%, p=0.028); adjusted PR=0.91 (95% CI: 0.83-0.99).

How the study worked

Generalized linear mixed-effects modeling using data from two community-recruited prospective cohorts of people who use drugs in Vancouver, Canada (2016-2018), with both cannabis use and fentanyl exposure verified by urine drug testing.

What this study cannot tell us

Observational design cannot prove causation; modest effect size; potential unmeasured confounders; urine testing captures recent use but not patterns; specific to Vancouver's drug supply.

How to read the evidence

Prospective cohort with objective urine testing and adjusted analysis, limited by observational design and modest effect size.

When this study was published

Data from 2016-2018 in Vancouver, Canada.

The bigger picture

These findings align with emerging evidence that cannabis may serve as a substitute for more dangerous substances in some contexts, though the effect size is modest and controlled trials are needed before cannabis could be recommended as a harm-reduction strategy.

Questions still open

Would controlled cannabinoid administration further reduce fentanyl exposure? Does the type of cannabis product matter for harm reduction in this population?

Common questions

Can cannabis reduce opioid use?

This study found that people on opioid therapy who used cannabis were slightly less likely to test positive for fentanyl. However, the effect was modest (9% reduction) and the study cannot prove cannabis caused the reduction.

How was this measured?

Both cannabis use and fentanyl exposure were measured objectively through urine drug testing, rather than self-report, making the findings more reliable.

Read the original research

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, 219, 108420

View on PubMed ↗Publisher’s paper ↗

Citation

Socías, M Eugenia; Choi, JinCheol; Lake, Stephanie; Wood, Evan; Valleriani, Jenna; Hayashi, Kanna; Kerr, Thomas; Milloy, M-J. (2021). 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, 219, 108420. https://doi.org/10.1016/j.drugalcdep.2020.108420