Endocannabinoid System: Cannabis for Chronic Pain Evidence

Clinical Takeaway

Cannabinoids, particularly products with measurable THC content, show modest but consistent evidence for reducing chronic pain compared to placebo in randomized controlled trials, though the overall certainty of evidence remains low to moderate. Benefits must be weighed against known harms, and patient selection, product formulation, and administration route all influence clinical outcomes. Clinicians should approach cannabinoid recommendations with individualized care rather than applying a one-size-fits-all protocol.

#1 Cannabis-Based Products for Chronic Pain : An Updated Systematic Review.

Citation: Chou Roger et al.. Cannabis-Based Products for Chronic Pain : An Updated Systematic Review.. Annals of internal medicine. 2026. PMID: 41429020.

Study type: Journal Article, Systematic Review, Review  |  Topic area: Pain  |  CED Score: 16

Design: 5 Journal: 3 N: 4 Recency: 3 Pop: 2 Human: 1 Risk: -2

Why This Matters
This systematic review provides updated evidence on the efficacy and safety profile of cannabinoid products across different THC-to-CBD ratios for chronic pain management, addressing a significant clinical knowledge gap given the expanding medical cannabis landscape and regulatory changes. The dual-reviewed risk of bias assessment and strength of evidence evaluation across multiple databases enables clinicians to make informed decisions about cannabinoid prescription and patient counseling, particularly important given the current lack of consensus on cannabinoid efficacy for chronic pain conditions.

Quality Gate Alerts:

  • Preclinical only

Abstract: BACKGROUND: Benefits and harms of cannabinoids for chronic pain are uncertain. PURPOSE: To update an evidence synthesis on cannabinoids for chronic pain. DATA SOURCES: Ovid MEDLINE, PsycINFO, Embase, the Cochrane Library, and Scopus to 28 July 2025. STUDY SELECTION: Randomized placebo-controlled trials. DATA EXTRACTION: Data extraction, risk of bias, and strength of evidence were dually reviewed. Cannabinoids were categorized by tetrahydrocannabinol (THC)-to-cannabidiol (CBD) ratio (high, comparable, or low), source (synthetic, purified, extracted), and administration method. DATA SYNTHESIS: 25 short-term (1 to 6 months) randomized controlled trials (n = 2303; 64% neuropathic pain) assessed cannabinoids. Oral synthetic/purified high THC-to-CBD (THC only) may slightly reduce and oromucosal, extracted, comparable THC-to-CBD ratio products probably slightly reduce pain severity (pooled differences, -0.78 and -0.54 points, respectively, [0 to 10 scale]), with moderate or large increased dizziness, sedation, and nausea. Among THC-only products, nabilone moderately reduced pain severity but dronabinol did not (pooled differences, -1.59 and -0.23 points, respectively). Low THC-to-CBD interventions may not improve outcomes. Although low THC-to-CBD mixed THC/CBD products may increase dizziness, sedation, and nausea, CBD alone may not increase harms. LIMITATION: Variability within categories; lack of product details; unclear U.S. availability of studied products; restricted to English-language studies. CONCLUSION: Comparable and high THC-to-CBD ratio cannabinoid products may result in small improvements in pain and increased common adverse events during short-term treatment of primarily neuropathic pain; among high-ratio THC-only products, nabilone (but not dronabinol) reduced pain. Low THC-to-CBD products may not improve outcomes. Studies are needed on long-term outcomes and other cannabis product types. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality, U.S

Clinical Perspective

💊 While this updated systematic review offers valuable clarity on cannabinoid efficacy for chronic pain, clinicians should recognize that heterogeneity in cannabinoid formulations, THC-to-CBD ratios, dosing protocols, and patient populations creates substantial variability in reported outcomes that may not easily translate to individual patient care. The quality of cannabis medicine evidence remains limited by regulatory constraints on research, relatively short trial durations that don’t capture long-term safety or tolerance patterns, and the relative scarcity of head-to-head comparisons with conventional analgesics or other non-pharmacologic interventions. Additionally, publication bias toward positive findings and the evolving landscape of cannabis products available outside clinical trial settings mean that evidence from controlled studies may diverge significantly from real-world patient experiences. For practitioners considering cannabinoids in chronic pain management, this review provides a useful framework for understanding current evidence, but clinical decision-making should incorporate individualized risk-benefit assessment, careful documentation of baseline pain and functional status, and close monitoring for adverse effects or drug

Full Article  |  PubMed