Cannabinoids Show Promise for Chronic Pain, But Evidence Remains Thin

A 2025 narrative review by Mayo Clinic-affiliated authors surveys the history, pharmacology, clinical evidence, and regulatory barriers surrounding cannabinoid use for chronic pain, finding moderate efficacy signals across several conditions but consistently low-quality evidence that falls short of supporting firm clinical recommendations.

Why This Matters

Chronic pain affects tens of millions of Americans, and the opioid crisis has intensified demand for alternatives that patients and clinicians can trust. Cannabinoids are already widely used outside formal medical guidance, creating a clinical reality that outpaces the evidence base. A current, honest accounting of what cannabinoid research actually shows, and where it falls short, is essential for clinicians navigating patient expectations shaped more by advocacy and anecdote than by controlled data.

Clinical Summary

This narrative review, published in Biomedicines in February 2025 by eight authors affiliated with Mayo Clinic and two U.S. medical schools, synthesizes existing literature on cannabinoids for chronic pain management. The paper spans the history of cannabis use for pain from antiquity through the present, describes the endocannabinoid system’s role in nociception and inflammation, and examines clinical evidence across neuropathic pain, fibromyalgia, cancer-related pain, and multiple sclerosis-related spasticity. The mechanistic rationale centers on the modulation of CB1 and CB2 receptors in pain pathways, with THC, CBD, and synthetic analogs each acting through partially distinct mechanisms that may complement existing analgesics.

The authors conclude that cannabinoids demonstrate moderate efficacy signals for each of these conditions, and they note patient-reported data suggesting cannabinoids are perceived as safer than opioids, with potential opioid-sparing effects. However, the review is candid that no condition is supported by large, high-quality randomized controlled trials. Evidence quality is repeatedly characterized as limited by small sample sizes, short study durations, and methodological inconsistencies. Safety concerns, including psychiatric effects, dependence potential, and drug interactions, are acknowledged as unresolved. The authors call for large-scale RCTs with long-term follow-up and note that the U.S. Schedule I classification of cannabis has materially hindered the research needed to answer these questions definitively.

Dr. Caplan’s Take

This review does a good job of laying out the landscape honestly. The biological rationale for cannabinoids in pain modulation is real, and the signals from smaller studies are genuinely worth pursuing. But what I tell patients is that “promising” and “proven” are not the same thing. When someone comes to me having read that cannabis helps chronic pain, I need to explain that the studies behind that claim are mostly small, short, and inconsistent. The gap between mechanistic plausibility and clinical certainty remains wide.

In practice, I approach cannabinoids as one component of a broader integrative pain strategy, never as a standalone replacement for evidence-based treatments. For patients already using cannabis, I focus on harm reduction, monitoring for psychiatric effects and drug interactions, and ensuring they are not abandoning therapies with stronger evidence behind them. I am willing to consider cannabinoid-based approaches in carefully selected patients who have not responded to first-line options, but always with transparent conversations about the limits of what we actually know.

Clinical Perspective

This review sits early in the research arc for cannabinoids in pain management, offering a contextual overview rather than definitive guidance. It confirms what prior systematic reviews and Cochrane analyses have found: there are signals of benefit, particularly for neuropathic pain and MS-related spasticity, but the evidence base lacks the rigor required for strong clinical recommendations. The proposed rescheduling of cannabis from Schedule I to Schedule III in the United States could eventually facilitate the large trials needed, but that change had not taken effect at the time of publication. Clinicians should understand that patient-reported perceptions of safety and opioid-sparing effects, while clinically interesting, derive largely from observational and self-report data that cannot establish causation.

From a pharmacological standpoint, cannabinoid-drug interactions deserve particular attention. THC and CBD are metabolized through cytochrome P450 pathways, and CBD in particular is a potent inhibitor of CYP3A4 and CYP2D6, creating meaningful interaction potential with opioids, benzodiazepines, anticonvulsants, and anticoagulants. Psychiatric risks, including anxiety exacerbation and psychosis vulnerability, require screening before initiation. The single most actionable step clinicians can take now is to proactively ask patients about cannabinoid use, document it, check for interactions with existing medications, and frame any trial of cannabinoids within a structured, monitored plan rather than passive acceptance of self-directed use.

Study at a Glance

Study Type

Narrative review

Population

Adults with chronic pain conditions including neuropathic pain, fibromyalgia, cancer-related pain, and MS-related spasticity

Intervention

Cannabinoids including THC, CBD, and synthetic analogs

Comparator

Standard analgesic therapies and placebo (as reported in cited trials)

Primary Outcomes

Pain reduction, patient-reported safety perceptions, opioid-sparing effects

Sample Size

Not applicable (narrative review of multiple studies)

Journal

Biomedicines (MDPI, open access)

Year

2025

DOI or PMID

Published February 20, 2025; specific DOI not provided in extracted text

Funding Source

Not reported

What Kind of Evidence Is This

This is a narrative review, which occupies a relatively low position in the evidence hierarchy compared to systematic reviews, meta-analyses, or randomized controlled trials. It does not describe a systematic search strategy, PRISMA protocol, or formal quality assessment of included studies. The most important inference constraint this imposes is that the selection of cited evidence may be incomplete or reflect the authors’ interpretive preferences, meaning its conclusions should be treated as informed opinion rather than comprehensive synthesis.

How This Fits With the Broader Literature

The conclusions here are broadly consistent with prior systematic reviews, including the 2018 Cochrane review on cannabis-based medicines for chronic neuropathic pain and the 2017 National Academies of Sciences report, both of which found limited but suggestive evidence for cannabinoid efficacy in select pain populations. This review adds value primarily through its updated regulatory discussion and its integration of the opioid-sparing hypothesis, though it does not materially advance the evidence beyond what those earlier syntheses established. The persistent finding across years and reviews is the same: the signals are interesting, but the trials needed to confirm or refute them have not been conducted.

Common Misreadings

The most likely overinterpretation is reading “moderate efficacy” as established clinical effectiveness. The review uses this language to characterize signals from small, short, and methodologically inconsistent studies, not findings from definitive trials. Clinicians and patients may also misread the opioid-sparing discussion as evidence that cannabinoids can replace opioids, when in fact this claim rests primarily on patient self-report and observational data without controlled confirmation. The favorable framing of cannabinoid safety relative to opioids, while contextually reasonable, should not obscure the real psychiatric and pharmacological risks that remain incompletely characterized.

Bottom Line

This narrative review provides a useful clinical overview of cannabinoids for chronic pain but does not materially strengthen the evidence base. The biological rationale is credible, the efficacy signals are real but weak, and the safety profile requires more rigorous characterization. No current evidence supports recommending cannabinoids as a first-line pain treatment. Clinicians should engage patients about their cannabinoid use, monitor for interactions and psychiatric effects, and await the large-scale trials that regulatory rescheduling may eventually enable.

References

1. Biomedicines. 2025 Feb 20. Narrative review on cannabinoids and chronic pain management. Mayo Clinic-affiliated authors (8). MDPI open access. Specific DOI not provided in extracted text.
2. Mucke M, Phillips T, Radbruch L, Petzke F, Hauser W. Cannabis-based medicines for chronic neuropathic pain in adults. Cochrane Database Syst Rev. 2018;3:CD012182. DOI: 10.1002/14651858.CD012182.pub2.
3. National Academies of Sciences, Engineering, and Medicine. The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research. Washington, DC: The National Academies Press; 2017. DOI: 10.17226/24625.