Highlights
- Prospective cohort data indicates that a 30-day supply of medical cannabis is associated with a reduction of 3.53 Morphine Milliequivalents (MME) per day among chronic pain patients.
- In cancer populations, the opening of medical cannabis dispensaries is associated with a significant decrease in opioid prescription rates (-41.07 per 10,000 patients).
- The opioid-sparing effect of cannabis persists even after accounting for unregulated (non-program) cannabis use.
- While both medical and recreational dispensaries correlate with reduced opioid dispensing, medical frameworks show a more pronounced impact on clinical outcomes.
Background
The dual crises of chronic pain prevalence and the opioid epidemic have necessitated a critical search for effective analgesic alternatives. Chronic pain affects a substantial portion of the adult population, frequently leading to long-term opioid therapy, which carries significant risks of misuse, overdose, and hyperalgesia. In recent years, medical cannabis has emerged as a primary candidate for opioid substitution. Despite increasing legalization, clinical and policy-level evidence regarding its efficacy in reducing “opioid receipt”—the actual dispensation of prescribed opioids—has remained fragmented. Clinicians require robust, prospective data to understand whether cannabis serves as a true substitute or a mere adjunct that does not alter opioid trajectories.
Key Content
Prospective Evidence in Chronic Non-Cancer Pain
A significant advancement in this field is the prospective cohort study conducted within the New York State (NYS) medical cannabis program (Slawek et al., 2025). This study followed 204 adults newly certified for medical cannabis who were already receiving opioids for chronic pain. Over an 18-month follow-up period, the research utilized Prescription Monitoring Program (PMP) data to provide an objective measure of opioid receipt.
The findings revealed a meaningful downward trend in opioid consumption. At baseline, the mean daily dose was 73.3 MME. By the end of the follow-up, this dropped to 57.4 MME. Using marginal structural models to account for both time-invariant and time-varying confounders, the researchers found that every 30 days of medical cannabis coverage was associated with 3.53 fewer MME per day (β = -3.53; 95% CI, -6.68 to -0.04; P = .03). Notably, this association remained significant even when controlling for self-reported unregulated cannabis use, suggesting that the formal medical program structure provides a specific therapeutic benefit in dose reduction.
Impact on Cancer-Related Pain and Health Policy
While the NYS study focused on individual-level dose reduction, broader systemic impacts have been observed in cancer populations. A cross-sectional study using synthetic control methods analyzed data from over 3 million commercially insured patients with cancer between 2007 and 2020 (Lozano-Rojas et al., 2025). This study investigated how the physical availability of dispensaries influenced opioid dispensing patterns.
The results were striking across multiple metrics:
- Prescription Rates: Medical cannabis dispensary openings were associated with a reduction of 41.07 patients receiving opioids per 10,000 patients (P < .001).
- Supply Duration: The mean days’ supply per prescription decreased by 2.54 days (P < .001).
- Recreational vs. Medical: While recreational dispensary openings also reduced opioid outcomes, the effect was smaller (reduction of 20.63 patients per 10,000; P = .049), suggesting that medical-grade products or the accompanying clinical guidance may be more effective for pain management than the recreational market alone.
Methodological Advances in Cannabis Research
Recent research has moved beyond simple cross-sectional surveys, which are often prone to recall bias. The integration of state-level Prescription Monitoring Program (PMP) data with dispensary records allows for a more accurate triangulation of “exposure” (cannabis use) and “outcome” (opioid receipt). Furthermore, the use of marginal structural models and synthetic control groups provides a higher level of causal inference, adjusting for the complexities of patient self-selection into cannabis programs.
Expert Commentary
The synthesis of these findings suggests that medical cannabis acts as a viable “opioid-sparing” agent. From a mechanistic perspective, the synergistic interaction between the endocannabinoid system and the mu-opioid receptors may allow for adequate analgesia at lower opioid dosages, potentially mitigating the risk of respiratory depression and opioid use disorder.
However, several controversies remain. First, while MME receipt decreased, the reduction in the NYS study (-3.53 MME) was modest. Clinicians must weigh whether this reduction is clinically significant enough to offset the potential side effects of cannabis, such as cognitive impairment or cardiovascular risks. Second, there is a lack of standardization in cannabis dosing; unlike opioids, cannabis products vary wildly in THC:CBD ratios. Finally, as noted in the cancer-related study, the presence of a legal market does not automatically equate to clinical efficacy for all patients. Direct observation of patient-reported outcomes (PROs) alongside dispensing data is necessary to ensure that reduced opioid receipt does not lead to undertreated pain.
Conclusion
The evidence from 2018–2025 marks a pivotal shift in our understanding of cannabis-opioid substitution. Participation in structured medical cannabis programs is associated with objective reductions in opioid dosage and prescription frequency across both chronic and cancer pain populations. These findings support the inclusion of medical cannabis as a component of multimodal pain management strategies. Future research should prioritize randomized controlled trials to establish optimal cannabinoid ratios for specific pain phenotypes and investigate the long-term safety profile of cannabis when used as a primary analgesic substitute.
References
- Slawek DE, Zhang C, Dahmer S, et al. Medical Cannabis and Opioid Receipt Among Adults With Chronic Pain. JAMA Intern Med. 2025;e256496. doi:10.1001/jamainternmed.2025.6496. PMID: 41359313.
- Lozano-Rojas F, Bethel V, Gupta S, et al. Cannabis Laws and Opioid Use Among Commercially Insured Patients With Cancer Diagnoses. JAMA Health Forum. 2025;6(10):e253512. doi:10.1001/jamahealthforum.2025.3512. PMID: 41105418.
