Medical Cannabis Matched Opioids for Chronic Pain in Network Meta-Analysis, but Benefits Were Modest
A 2024 systematic review found that medical cannabis and opioids produced broadly similar short-term improvements in pain, sleep quality, and physical functioning among adults with chronic non-cancer pain. The analysis also found that patients receiving medical cannabis were less likely than those taking opioids to stop treatment because of adverse effects in studies that did not use an “enrichment” design.
The study, published in BMJ Open, was a systematic review and network meta-analysis of 90 randomized controlled trials involving 22,028 participants. Because only one trial directly compared cannabis with opioids, the researchers primarily made indirect comparisons by examining how each treatment performed against placebo.
The findings do not show that cannabis is universally as effective as opioids, nor that it is a safer replacement in every circumstance. Instead, they suggest that the average benefits of both treatments are modest. Compared with placebo, the researchers estimated that roughly 10% to 15% more patients might achieve a clinically meaningful improvement in pain, depending on the treatment and outcome being measured.
Similar effects on pain, sleep, and function
The analysis found little or no difference between medical cannabis and opioids in pain relief. The same was true for sleep quality, although the evidence for that outcome was considered low certainty. Evidence for physical functioning was somewhat stronger and also suggested little or no meaningful difference between the two treatments.
Neither treatment showed clear benefits over placebo for emotional, social, or role functioning. The researchers emphasized that the results describe average effects across groups; individual patients may respond differently, and a treatment that helps one person may provide little benefit to another.
The review’s findings are consistent with earlier evidence that non-inhaled cannabis products can provide small improvements in pain and sleep compared with placebo. A 2021 BMJ systematic review, for example, found modest benefits from oral or topical cannabis products but also reported increased risks of dizziness, drowsiness, nausea, impaired attention, and other transient side effects.
Fewer treatment dropouts, but not necessarily fewer side effects
In non-enriched trials—studies in which participants were not first selected because they tolerated or responded to treatment—patients assigned to medical cannabis were less likely to discontinue treatment because of adverse events than those assigned to opioids. The estimated odds of discontinuation were about 45% lower for cannabis in this group, although the researchers rated the direct comparison as low-certainty evidence.
That finding should not be interpreted as proof that cannabis causes fewer adverse events overall. The study measured whether participants stopped treatment because of side effects rather than comparing every individual symptom. Other research has associated medical cannabis, particularly products containing tetrahydrocannabinol, with dizziness, sedation, cognitive effects, nausea, and impaired attention.
Opioids carry serious risks that are difficult for relatively short randomized trials to measure, including opioid use disorder and fatal or non-fatal overdose. The researchers noted that cannabis does not produce the same degree of respiratory depression as opioids. However, the review was not designed to determine whether cannabis is safer over the long term or whether it prevents overdose, addiction, or other rare harms.
Important limits to the evidence
Most of the included studies were judged to have a high risk of bias in at least one area, and many had substantial missing outcome data. Follow-up was generally short, limiting what the analysis can say about long-term effectiveness and safety.
The evidence also applies mainly to specific medical cannabis or cannabinoid products studied in clinical trials—not necessarily to all products sold in dispensaries or used outside medical supervision. None of the eligible trials evaluated inhaled cannabis, including smoked or vaporized products. The results therefore cannot be assumed to apply to those forms of administration.
The study also did not establish that cannabis reduces the need for opioids. Determining whether cannabis can safely substitute for or reduce opioid doses requires trials designed specifically to measure opioid use, as well as longer-term follow-up.
What the findings mean for treatment decisions
The authors concluded that medical cannabis may be similarly effective to opioids for some aspects of chronic non-cancer pain, but the certainty of the evidence ranged from low to moderate and the size of the benefit was small. Their results support considering cannabis-based medicines as one possible option in carefully selected patients, not as a universally safer or more effective replacement for opioid therapy.
For people already taking opioids, changing the dose or stopping treatment without medical guidance can be dangerous. The CDC’s clinical guideline for prescribing opioids recommends individualized, patient-centered decisions that weigh benefits, risks, alternatives, and treatment goals.
Overall, the evidence points to a limited but potentially useful role for medical cannabis in chronic pain care. More direct head-to-head trials, longer studies, and research involving real-world products and inhaled formulations are needed before clinicians can draw firm conclusions about which patients are most likely to benefit and how the long-term risks compare with those of opioids.
