Medical Cannabis for Chronic Pain: Promise, Pharmacology, and Persistent Gaps

A 2025 narrative review maps the pharmacology and clinical rationale for cannabinoids in chronic pain management, but the absence of systematic evidence synthesis, standardized dosing, and long-term safety data means that strong conclusions about efficacy or safety remain premature.

Why This Matters

Chronic pain affects hundreds of millions of people worldwide, and the well-documented harms of long-term opioid therapy have created urgent demand for credible analgesic alternatives. Cannabinoids are among the most commonly discussed options by patients and clinicians alike, yet the gap between public enthusiasm and rigorous evidence remains substantial. A review consolidating the current mechanistic and clinical landscape arrives at a moment when clinicians need to distinguish between biological plausibility and proven benefit, and when patients increasingly expect informed guidance on cannabis-based treatments.

Clinical Summary

Chronic pain conditions, particularly neuropathic pain, multiple sclerosis-related spasticity, and inflammatory arthritis, remain inadequately managed for many patients despite existing pharmacotherapy. Published in Stresses (MDPI) in January 2025, this narrative review by Morales-Ruiz and colleagues surveys the pharmacology of the endocannabinoid system, the properties of major phytocannabinoids (principally delta-9-THC and CBD), and the clinical literature supporting their use in chronic pain. The mechanistic rationale is coherent: THC acts as a partial agonist at CB1 and CB2 receptors distributed throughout the central and peripheral nervous systems, modulating nociceptive signaling, while CBD exerts anti-inflammatory and neuromodulatory effects through non-CB1/CB2 pathways.

The authors report that clinical evidence supports cannabinoid benefit for neuropathic pain, MS-related pain, arthritis, and cancer-associated pain, particularly in patients who have not responded to conventional treatments. Several FDA-approved cannabinoid products, including Epidiolex, Sativex, nabilone, and dronabinol, already exist for specific indications, though chronic pain is not uniformly among them. However, the review does not employ a systematic search strategy, does not assess the quality of the trials it cites, and does not report effect sizes. The authors themselves acknowledge that standardized dosing protocols, long-term safety surveillance data, robust drug interaction profiles, and coherent regulatory frameworks are all absent. They conclude that these gaps must be addressed through large-scale, well-designed clinical trials before cannabinoids can be broadly integrated into routine pain management.

Dr. Caplan’s Take

This review does a reasonable job of laying out the mechanistic case for cannabinoid analgesia. The endocannabinoid system is real, its role in pain modulation is well established, and there is nothing implausible about the idea that plant-derived or synthetic cannabinoids could offer meaningful relief for some patients. The problem is that a biologically coherent story is not the same as clinical proof. Patients ask me about medical cannabis for pain regularly, and an honest answer requires acknowledging that we have promising signals but not the kind of dose-finding, long-term, head-to-head trial data that would let me prescribe with the same confidence I bring to better-studied analgesics.

In practice, I approach cannabis-based interventions as part of a broader, individualized pain management strategy rather than as a standalone solution. For patients who have genuinely exhausted conventional options and who understand the current evidence limitations, I am willing to discuss a cautious trial, particularly with CBD-predominant formulations where the side effect profile is more favorable. But I insist on close follow-up, realistic expectations, and documentation of functional outcomes rather than reliance on subjective pain scores alone. The evidence is not yet strong enough to justify enthusiasm, but it is strong enough to justify continued investigation.

Clinical Perspective

This review sits early in the research arc for cannabinoids in chronic pain, functioning as a broad orientation document rather than a definitive evidence synthesis. It confirms what the field has known for some time: the pharmacological rationale is sound, a handful of approved products exist for adjacent indications, and certain pain conditions (neuropathic pain, MS spasticity) have more supporting signal than others. What it does not do is resolve any of the critical translational questions. Without systematic search methods, formal quality appraisal, or meta-analytic pooling, the review cannot tell clinicians how large the expected benefit is, how it compares to active comparators, or which patient subgroups are most likely to respond. This means patient-facing recommendations based on this document alone would be premature.

From a safety and pharmacology standpoint, THC carries established risks including cognitive impairment, psychosis exacerbation, dependency potential, and cardiovascular effects that deserve particular caution in elderly or psychiatrically vulnerable populations. CBD, while generally better tolerated, is a potent inhibitor of cytochrome P450 enzymes (especially CYP3A4 and CYP2C19), creating clinically meaningful drug interaction potential with anticoagulants, antiepileptics, and immunosuppressants. Clinicians considering cannabinoid therapy should conduct a thorough medication reconciliation, start with low doses, titrate slowly, and schedule structured reassessment at defined intervals to evaluate both efficacy and tolerability before continuing treatment.

Study at a Glance

Study Type

Narrative review (non-systematic)

Population

Adults with chronic pain conditions including neuropathy, MS, arthritis, and cancer pain (no original patient data)

Intervention

Cannabinoids, principally delta-9-THC and CBD, across multiple formulations

Comparator

Not applicable (no original comparative data)

Primary Outcomes

Pain intensity reduction; secondary outcomes include safety, tolerability, and regulatory considerations

Sample Size

Not applicable (review article with no original data)

Journal

Stresses (MDPI)

Year

2025

DOI

10.3390/stresses5010007

Funding Source

Not reported

What Kind of Evidence Is This

This is a narrative review, which occupies one of the lower tiers in the evidence hierarchy for informing clinical decisions. Unlike systematic reviews or meta-analyses, narrative reviews do not follow a pre-specified search protocol, do not apply formal inclusion and exclusion criteria, and do not assess the methodological quality of the studies they cite. The single most important inference constraint this imposes is that the completeness and representativeness of the cited literature cannot be independently verified, making the conclusions inherently susceptible to selection bias and author interpretation.

How This Fits With the Broader Literature

The review’s mechanistic claims align with well-established pharmacology of the endocannabinoid system. Its clinical claims are broadly consistent with, though less rigorous than, prior systematic reviews such as the 2018 Cochrane review by Mucke and colleagues on cannabis-based medicines for chronic neuropathic pain, which found low-quality evidence of modest benefit alongside significant adverse event rates. A 2015 systematic review and meta-analysis by Whiting and colleagues in JAMA similarly reported moderate-quality evidence for cannabinoid benefit in chronic pain, while noting frequent adverse effects. The present review does not advance beyond these prior syntheses in methodological rigor and, by virtue of its narrative design, provides a less reliable summary of the same territory they covered more systematically.

Common Misreadings

The most likely overinterpretation is treating this review as confirmation that medical cannabis “works” for chronic pain in a clinically actionable sense. The review summarizes a biologically plausible rationale and selectively cites supportive clinical studies, but it does not quantify effect sizes, does not compare cannabinoids against active standard-of-care treatments, and does not assess the quality of the evidence it draws upon. Concluding from this document that cannabinoids should be recommended as a routine analgesic option would exceed what the evidence, as presented here, can support. The existence of FDA-approved cannabinoid products for specific indications should not be conflated with regulatory endorsement for chronic pain broadly.

Bottom Line

This narrative review provides a useful orientation to cannabinoid pharmacology and the clinical landscape for chronic pain, but it generates no new evidence and cannot substitute for a systematic evidence synthesis. Cannabinoids remain biologically plausible analgesic candidates with some clinical signal in neuropathic pain and MS-related conditions, but standardized dosing, long-term safety data, and rigorous head-to-head trials are still needed before routine clinical recommendation is warranted.

References

1. Morales-Ruiz P, et al. The role of medical cannabis in the management of chronic pain: a review. Stresses. 2025;5(1):7. DOI: 10.3390/stresses5010007.
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(3):CD012182. DOI: 10.1002/14651858.CD012182.pub2.
3. Whiting PF, Wolff RF, Deshpande S, et al. Cannabinoids for medical use: a systematic review and meta-analysis. JAMA. 2015;313(24):2456-2473. DOI: 10.1001/jama.2015.6358.