A prospective cohort study of 204 chronic pain patients found that participation in New York's medical cannabis program was associated with 3.53 fewer daily morphine milliequivalents for each month of full cannabis dispensation, even after accounting for unregulated cannabis use.
Chronic pain patients on opioids considering medical cannabis, prescribers managing opioid therapy, policymakers evaluating medical cannabis programs, and addiction researchers.
3.53 fewer daily MME per 30-day cannabis supply (JAMA Internal Medicine)
What the researchers found
Compared to months with no medical cannabis dispensed, a 30-day supply of medical cannabis was associated with 3.53 fewer daily morphine milliequivalents (MME). Mean daily MME decreased from 73.3 at baseline to 57.4 over 18 months of follow-up. The analysis used marginal structural models controlling for unregulated cannabis use.
Why it matters
Published in JAMA Internal Medicine, this is one of the most methodologically rigorous studies on medical cannabis and opioid substitution. The use of prescription monitoring data (not just self-report) and marginal structural models accounting for unregulated cannabis use strengthens the causal inference.
The numbers in context
204 participants, mean age 56.8, 55.4% female. Baseline pain severity 6.6/10, pain interference 6.8/10. Baseline daily MME: 73.3, decreasing to 57.4 over 18 months. 30-day cannabis supply associated with 3.53 fewer daily MME (95% CI: -6.68 to -0.04, p=.03).
How the study worked
Prospective cohort study using New York State Prescription Monitoring Program data from September 2018 to July 2023. 204 adults with chronic pain who were prescribed opioids and newly certified for medical cannabis were followed for 18 months. Monthly cannabis dispensation was monitored and linked to opioid prescription data.
What this study cannot tell us
Observational cohort without randomization. Bronx, New York setting may not generalize to other populations. Moderate sample of 204 patients. Cannabis dispensation data may not perfectly capture actual consumption. The 3.53 MME reduction, while statistically significant, is modest.
How to read the evidence
Strong: prospective cohort with prescription monitoring data, marginal structural models adjusting for time-varying confounders including unregulated cannabis, published in a top-tier journal.
When this study was published
Published 2026. Data from September 2018 to July 2023.
The bigger picture
This JAMA Internal Medicine study adds to growing evidence that medical cannabis programs may support opioid reduction. Uniquely, it accounts for unregulated cannabis use, addressing a major confounder that most previous studies ignored.
Questions still open
- Is the 3.53 MME reduction clinically meaningful for individual patients? Would results differ with higher-THC or different cannabinoid formulations? Does the opioid reduction translate to improved pain outcomes or quality of life?
Common questions
Can medical cannabis reduce opioid use for chronic pain?
Does this study account for people using cannabis outside of dispensaries?
Read the original research
Medical Cannabis and Opioid Receipt Among Adults With Chronic Pain.
JAMA internal medicine, 186(2), 252-261
Citation
Slawek, Deepika E; Zhang, Chenshu; Dahmer, Stephen; Sohler, Nancy; Zolotov, Yuval; Starrels, Joanna L; Deng, Yuting; Calderon DiFrancesca, Giovanna; Levin, Frances R; Ross, Jonathan; Minami, Haruka; Cunningham, Chinazo O; Arnsten, Julia H. (2026). Medical Cannabis and Opioid Receipt Among Adults With Chronic Pain.. JAMA internal medicine, 186(2), 252-261. https://doi.org/10.1001/jamainternmed.2025.6496
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