Daily cannabis use was associated with 26% faster cessation of opioid injection in people who inject drugs
In a 13-year prospective study of people who inject drugs in Vancouver, daily cannabis use was associated with 26% faster cessation of opioid injection specifically, without increasing injection relapse risk.
Quick Facts
What This Study Found
Among three prospective cohorts of people who inject drugs (PWID) in Vancouver from 2005-2018, at-least-daily cannabis use was associated with 16% faster injection cessation overall (AHR 1.16, CI 1.03-1.30). The effect was driven entirely by opioid injection cessation (AHR 1.26, CI 1.12-1.41), with no significant association for other drug injection cessation. Daily cannabis use was not associated with injection relapse (AHR 1.08, CI 0.95-1.23).
Key Numbers
13-year follow-up (2005-2018); daily cannabis: 16% faster injection cessation overall (AHR 1.16); 26% faster opioid injection cessation specifically (AHR 1.26); no significant injection relapse risk (AHR 1.08).
How They Did This
Extended Cox regression analysis with time-updated covariates from three prospective cohorts of PWID in Vancouver, Canada (2005-2018), examining associations between cannabis use frequency and injection cessation and relapse.
Why This Research Matters
During an ongoing opioid overdose crisis, any intervention that helps people stop injecting opioids is significant. The opioid-specific effect (not general injection cessation) suggests cannabis may address something unique about opioid dependence.
The Bigger Picture
This adds to a growing body of evidence suggesting cannabis may serve as an "exit drug" from opioids rather than a "gateway drug" to harder substances. The opioid-specific effect strengthens this argument.
What This Study Doesn't Tell Us
Observational (cannot establish causation); self-reported cannabis use and injection behavior; unmeasured confounders possible; Vancouver-specific harm reduction context may not generalize; cannot determine cannabis dose, potency, or route.
Questions This Raises
- ?Would structured medical cannabis programs help people who inject opioids transition to safer patterns?
- ?What mechanism explains the opioid-specific effect?
Trust & Context
- Key Stat:
- 26% faster opioid injection cessation with daily cannabis use
- Evidence Grade:
- Strong: large prospective design over 13 years with time-updated analysis and appropriate adjustments.
- Study Age:
- Published 2020.
- Original Title:
- Frequent Cannabis Use and Cessation of Injection of Opioids, Vancouver, Canada, 2005-2018.
- Published In:
- American journal of public health, 110(10), 1553-1560 (2020)
- Authors:
- Reddon, Hudson(5), DeBeck, Kora(8), Socias, M Eugenia(2), Lake, Stephanie, Dong, Huiru, Karamouzian, Mohammad, Hayashi, Kanna, Kerr, Thomas, Milloy, M-J
- Database ID:
- RTHC-02797
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Can cannabis help people stop injecting opioids?
In this 13-year study, daily cannabis use was associated with 26% faster cessation of opioid injection in people who inject drugs, without increasing relapse risk. However, this is observational and cannot prove cannabis caused the cessation.
Is cannabis a "gateway" or "exit" drug for opioids?
This study supports the "exit drug" hypothesis. Daily cannabis was associated with faster opioid injection cessation specifically, while not increasing the risk of returning to injection drug use.
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Cite This Study
https://rethinkthc.com/research/RTHC-02797APA
Reddon, Hudson; DeBeck, Kora; Socias, M Eugenia; Lake, Stephanie; Dong, Huiru; Karamouzian, Mohammad; Hayashi, Kanna; Kerr, Thomas; Milloy, M-J. (2020). Frequent Cannabis Use and Cessation of Injection of Opioids, Vancouver, Canada, 2005-2018.. American journal of public health, 110(10), 1553-1560. https://doi.org/10.2105/AJPH.2020.305825
MLA
Reddon, Hudson, et al. "Frequent Cannabis Use and Cessation of Injection of Opioids, Vancouver, Canada, 2005-2018.." American journal of public health, 2020. https://doi.org/10.2105/AJPH.2020.305825
RethinkTHC
RethinkTHC Research Database. "Frequent Cannabis Use and Cessation of Injection of Opioids,..." RTHC-02797. Retrieved from https://rethinkthc.com/research/reddon-2020-frequent-cannabis-use-and
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.