What Does Science Actually Know About Medical Cannabis?
What Researchers Found About Chronic Pain and Cannabis
The Study at a Glance
Published
JAMA, 2015
Researchers
University of Bristol (United Kingdom)
Study Type
Meta-AnalysisKey Finding
This comprehensive review of 79 trials found moderate-quality evidence that cannabinoids are effective for chronic pain and spasticity, with most studies showing improvement in symptoms.
Key Finding: This comprehensive review of 79 trials found moderate-quality evidence that cannabinoids are effective for chronic pain and spasticity, with most studies showing improvement in symptoms.
What Researchers Studied About Chronic Pain and Cannabis
This landmark JAMA study asked the fundamental question: What do we actually know about medical cannabis based on rigorous scientific evidence?
Researchers systematically reviewed 79 randomized controlled trials—the gold standard of medical research—to evaluate cannabinoids for various medical conditions.
This matters because it cuts through the hype and provides a clear picture of where the evidence is strong and where we need more research.
How This Meta-Analysis Was Conducted
Researchers conducted a comprehensive search of medical databases for all randomized controlled trials studying cannabinoids. They analyzed:
• 79 trials with a total of 6,462 participants • Studies on nausea/vomiting, appetite stimulation, chronic pain, spasticity, and more • Quality of evidence using the GRADE system • Both pharmaceutical cannabinoids and plant-based cannabis
Chronic Pain Treatment Results
The Main Results:
- 1Moderate-quality evidence that cannabinoids are effective for chronic pain
- 2Moderate-quality evidence supporting use for spasticity in multiple sclerosis
- 3Low-quality evidence for nausea from chemotherapy, weight gain in HIV, sleep disorders, and Tourette syndrome
- 4Most common side effects: dizziness, dry mouth, nausea, fatigue, somnolence
- 5Pharmaceutical cannabinoids showed consistent effects across studies
By the Numbers
| Statistic | What It Means |
|---|---|
| 79 | randomized controlled trials analyzed |
| 6,462 | total participants across all studies |
| 30% | greater improvement in chronic pain vs placebo |
| Moderate | quality of evidence for pain and spasticity |
randomized controlled trials analyzed
total participants across all studies
greater improvement in chronic pain vs placebo
quality of evidence for pain and spasticity
What This Means for Chronic Pain Patients
This comprehensive review gives us our clearest picture yet of what medical cannabis can reliably help with:
Strong evidence supports using cannabinoids for: • Chronic pain (especially neuropathic pain) • Muscle spasticity from MS or spinal cord injury
Emerging evidence suggests potential benefits for: • Chemotherapy-induced nausea • Appetite stimulation in HIV/AIDS • Sleep disorders
Talk to your doctor about whether cannabinoids might be appropriate for your condition, especially if you have chronic pain or muscle spasticity that hasn't responded well to other treatments.
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.
Is there scientific proof that medical marijuana works?
Yes, for certain conditions. A JAMA review of 79 trials found moderate-quality evidence that cannabinoids help chronic pain and MS spasticity, with 30% greater pain relief than placebo (Whiting et al., JAMA, 2015).
Source: Whiting et al., JAMA, 2015 (PMID: 26103030)
What conditions does cannabis actually treat?
Chronic pain and MS spasticity have the strongest evidence. A comprehensive JAMA review of 79 trials found moderate-quality evidence for these conditions, with lower-quality evidence for nausea, appetite, and sleep (Whiting et al., 2015).
Source: Whiting et al., JAMA, 2015 (PMID: 26103030)
How effective is cannabis compared to placebo for pain?
30% more effective than placebo. The JAMA meta-analysis of 79 trials found cannabinoids provide about 30% greater pain relief than placebo for chronic pain conditions (Whiting et al., 2015).
Source: Whiting et al., JAMA, 2015 (PMID: 26103030)
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:
- Many studies were small with short follow-up periods
- Studies used different cannabinoid preparations, doses, and routes
- Most studies were conducted with pharmaceutical cannabinoids, not whole-plant cannabis
- Publication bias may affect results (positive studies more likely to be published)
- Evidence for many conditions remains low quality
The Bottom Line on Cannabis for Chronic Pain
This JAMA meta-analysis provides our most reliable evidence that cannabinoids work for chronic pain and muscle spasticity. While more research is needed for other conditions, patients with these specific issues have good scientific backing to discuss cannabis with their doctors.
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
- Cannabis Benefits and Risks: What 101 Studies Reveal
- Cannabis for Chronic Pain: A Critical Look at 104 Studies
- Clinical Practice Guidelines: Cannabis for Chronic Pain & Co-Occurring Conditions (2024)
- Cannabis for Pain: A Complete Overview of the Evidence
- Medical Cannabis for Cancer Patients: Real-World Results
Condition Research
Get Your Card
This condition qualifies for medical marijuana in:
Source
Whiting PF, Wolff RF, Deshpande S, et al. "Cannabinoids for Medical Use: A Systematic Review and Meta-analysis" JAMA. 2015. DOI: 10.1001/jama.2015.6358
Important Information
Study Age: This study was published 11 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 24, 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
What did the JAMA 2015 study find about medical cannabis?
Yes, moderate-quality evidence supports effectiveness. The JAMA study reviewed 79 randomized controlled trials and found moderate-quality evidence that cannabinoids are effective for chronic pain and muscle spasticity, with lower-quality evidence for nausea, appetite, and sleep disorders.
Is there scientific evidence that cannabis helps with pain?
Yes. This JAMA meta-analysis found moderate-quality evidence from multiple clinical trials showing cannabinoids provide about 30% greater pain relief than placebo for chronic pain conditions.
What conditions have the strongest evidence for cannabis treatment?
Chronic pain and MS spasticity have the strongest evidence. According to this JAMA review, chronic pain and muscle spasticity (especially from MS) have the most scientific evidence supporting cannabinoid treatment.