Cannabis for Chronic Pain: What 43 Clinical Trials Show
What Researchers Found About Chronic Pain and Cannabis
The Study at a Glance
Published
Pain Physician, 2017
Researchers
Multiple institutions (International)
Study Type
Meta-AnalysisParticipants
2,437 patients · Varies by trial
Key Finding
Cannabis-based medicines might be effective for chronic pain treatment, based on limited evidence, primarily for neuropathic pain patients. However, the clinical significance of these findings is uncertain as the majority of studies did not show an effect.
Key Finding: Cannabis-based medicines might be effective for chronic pain treatment, based on limited evidence, primarily for neuropathic pain patients. However, the clinical significance of these findings is uncertain as the majority of studies did not show an effect.
What Researchers Studied About Chronic Pain and Cannabis
Chronic pain management is a complex challenge worldwide. Cannabis-based medicines have been reported to reduce chronic pain, but the topic remains highly controversial.
This systematic review and meta-analysis combined all randomized controlled trials to assess the efficacy and adverse events of cannabis-based medicines for chronic and postoperative pain treatment.
Researchers searched MEDLINE/PubMed and Google Scholar for all literature published up to July 2015.
How This Meta-Analysis Was Conducted
The review included 43 randomized controlled trials with 2,437 total patients. Of these, 24 RCTs (1,334 patients) were eligible for meta-analysis.
All included studies compared the analgesic effects of cannabis-based medicines to placebo. Study quality was assessed using the Jadad scale, and meta-analysis used random-effects models.
The researchers calculated Hedges' g effect sizes and assessed statistical heterogeneity.
Chronic Pain Treatment Results
The Main Results:
- 1Chronic pain overall: statistically significant reduction (SMD -0.61, 95% CI -0.78 to -0.43, P < 0.0001)
- 2Inhalation route showed stronger effect (SMD -0.93, 95% CI -1.51 to -0.35, P = 0.001)
- 3However, majority of individual studies did not show a clinically significant effect
- 4Best evidence was for neuropathic pain specifically
- 5Most prominent adverse events: central nervous system and gastrointestinal effects
- 6Oral/oromucosal routes had more GI adverse events than inhalation
By the Numbers
| Statistic | What It Means |
|---|---|
| 43 RCTs | Total trials reviewed (2,437 patients), with 24 RCTs (1,334 patients) in the meta-analysis |
| -0.61 | Standardized mean difference for chronic pain reduction vs placebo (statistically significant) |
| -0.93 | Stronger effect size when cannabis was inhaled rather than taken orally |
| P < 0.0001 | Statistical significance of the overall pain reduction finding |
Total trials reviewed (2,437 patients), with 24 RCTs (1,334 patients) in the meta-analysis
Standardized mean difference for chronic pain reduction vs placebo (statistically significant)
Stronger effect size when cannabis was inhaled rather than taken orally
Statistical significance of the overall pain reduction finding
What This Means for Chronic Pain Patients
If you have chronic pain, especially neuropathic pain, this analysis suggests cannabis-based medicines may help reduce pain compared to placebo.
However, the authors caution that the "clinical significance" is uncertain. While the overall statistical analysis showed benefit, the majority of individual studies did not show a meaningful effect. This means results are inconsistent.
Inhaled cannabis showed a stronger effect than oral forms. Common side effects involve the nervous system (dizziness, etc.) and digestive system (nausea, etc.), with oral forms causing more GI issues than inhalation.
This research suggests cannabis might be an option for neuropathic pain when other treatments have failed, but expectations should be realistic about the inconsistent evidence.
Quick Answers: Chronic Pain and Cannabis
Direct answers based on the findings of this study:
Research Summary: Answers are based on published peer-reviewed studies and represent research findings, not medical recommendations. Individual results may vary. Always consult a healthcare provider before making treatment decisions.
Does medical marijuana work for chronic pain?
Statistically yes, clinically uncertain. A 2017 meta-analysis of 43 trials found statistically significant pain reduction (P < 0.0001), primarily for neuropathic pain. However, the "clinical significance is uncertain."
Source: Aviram & Samuelly-Leichtag, Pain Physician, 2017 (PMID: 28934780)
Is smoking or eating marijuana better for pain?
Inhaled cannabis showed stronger pain relief (SMD -0.93) than oral forms (SMD -0.61) in this meta-analysis. Oral routes also caused more gastrointestinal side effects than inhalation.
Source: Aviram & Samuelly-Leichtag, Pain Physician, 2017 (PMID: 28934780)
What type of pain does cannabis help most?
Neuropathic pain showed the best evidence. The 2017 meta-analysis concluded cannabis-based medicines "might be effective... primarily for neuropathic pain patients," though results remain inconsistent.
Source: Aviram & Samuelly-Leichtag, Pain Physician, 2017 (PMID: 28934780)
This is educational content, not medical advice
The research summarized here is for informational purposes only. Individual results may vary, and what works in studies may not work the same way for everyone. Always consult with a qualified healthcare provider before making changes to your treatment plan or starting medical cannabis therapy.
Important Limitations
This study has some caveats to keep in mind when interpreting the results:
- Studies were extremely heterogeneous (different types, doses, conditions)
- Only English-language studies included
- Majority of individual studies did not show clinically significant improvement
- Only 7 studies reported on prior cannabis use history
- Inadequate blinding of placebo is a concern with cannabinoid studies
- Data only through July 2015
The Bottom Line on Cannabis for Chronic Pain
This meta-analysis of 43 trials found a statistically significant reduction in chronic pain with cannabis-based medicines, especially for neuropathic pain and when inhaled. However, the clinical significance is uncertain because most individual studies did not show meaningful effects. Cannabis may be worth considering for neuropathic pain that has not responded to other treatments, but results are inconsistent and expectations should be managed accordingly.
Do You Qualify for Medical Marijuana?
If you're living with Chronic Pain, you may qualify for a medical marijuana card. Our licensed physicians can evaluate you from home via telehealth.
Related Research & Resources
Related Research
Condition Research
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This condition qualifies for medical marijuana in:
Source
Aviram J, Samuelly-Leichtag G "Efficacy of Cannabis-Based Medicines for Pain Management: A Systematic Review and Meta-Analysis of Randomized Controlled Trials" Pain Physician. 2017.
Important Information
Study Age: This study was published 9 years ago. Newer research may have updated or refined these findings.
Not Medical Advice: This research summary is for educational purposes only. It should not be used to diagnose, treat, cure, or prevent any disease or medical condition. Always consult a qualified healthcare provider before starting or changing any treatment.
Individual Variation: Research findings represent group averages. Your individual response to cannabis may differ based on genetics, other medications, underlying conditions, and many other factors.
Last reviewed: January 25, 2026
Important Notices
Research Summary Disclaimer
This content represents our interpretation of published scientific research for educational purposes. It should not be used to make treatment decisions without consulting a qualified healthcare provider. Individual results may vary from study findings.
FDA Notice
These statements have not been evaluated by the FDA. Cannabis is not intended to diagnose, treat, cure, or prevent any disease. The FDA has not approved cannabis for any medical condition except specific prescription medications.
Copyright & Fair Use
Research summaries are provided under fair use (17 U.S.C. § 107) for educational purposes. We provide brief summaries with attribution, not full reproductions. All studies remain the intellectual property of their respective authors and publishers.
Data Sources
Study information sourced from PubMed®, U.S. National Library of Medicine. Inclusion does not imply endorsement by NLM, NIH, or the federal government.
For complete information, see our Terms of Use and Research Content Policy.
FAQs: Cannabis for Chronic Pain
Does cannabis help chronic pain?
Statistically yes, clinically uncertain. A meta-analysis of 43 trials found statistically significant pain reduction with cannabis (P < 0.0001), especially for neuropathic pain. However, most individual studies did not show clinically meaningful effects.
Is smoking or eating cannabis better for pain?
Inhaled cannabis had a stronger effect. This meta-analysis found inhaled cannabis (SMD -0.93) was more effective than oral/oromucosal forms (SMD -0.61). Oral forms also caused more gastrointestinal side effects.
What are cannabis side effects for pain?
CNS and GI side effects are most common. Dizziness and nausea are the most prominent adverse events. GI side effects were more common with oral/oromucosal routes than with inhalation.