15 of 18 high-quality trials found cannabinoids significantly reduced chronic pain compared to placebo | Research

The takeaway

A systematic review of 18 RCTs found 15 demonstrated significant analgesic effects of cannabinoids for chronic non-cancer pain, with excellent trial quality and no serious adverse effects.

Read this if you have chronic pain and want to know what the best evidence says about cannabinoid treatments.

83% of trials showed significant pain relief from cannabinoids

What the researchers found

Researchers systematically reviewed randomized controlled trials of cannabinoids for chronic non-cancer pain. Of 18 trials meeting inclusion criteria, 15 demonstrated a significant analgesic effect compared to placebo.

The review included studies of smoked cannabis, oromucosal cannabis extracts, nabilone, dronabinol, and a novel THC analogue. Pain conditions included neuropathic pain, fibromyalgia, rheumatoid arthritis, and mixed chronic pain.

Overall trial quality was described as "excellent." Several studies also reported significant improvements in sleep alongside pain relief.

There were no serious adverse effects across the trials. Most commonly reported side effects were generally well tolerated, mild to moderate in severity, and rarely led to study withdrawal.

The authors concluded there was evidence that cannabinoids were "safe and modestly effective" for neuropathic pain, with preliminary evidence for fibromyalgia and rheumatoid arthritis.

Why it matters

This was one of the most influential systematic reviews establishing cannabinoids as modestly effective analgesics for chronic pain, with 83% of high-quality trials showing significant benefit.

The numbers in context

18 RCTs met inclusion criteria. 15 of 18 (83%) showed significant analgesic effects. No serious adverse effects. Conditions: neuropathic pain, fibromyalgia, rheumatoid arthritis, mixed chronic pain. Multiple cannabinoid formulations studied.

How the study worked

Systematic review conducted according to PRISMA guidelines. Randomized controlled trials of cannabinoids for chronic non-cancer pain identified and evaluated for quality and outcomes.

What this study cannot tell us

Studies were heterogeneous in cannabinoid type, dose, duration, and pain condition. "Modest" effectiveness means the effect sizes were not large. Longer-term safety data were lacking.

How to read the evidence

Systematic review of high-quality RCTs following PRISMA guidelines, representing the strongest form of clinical evidence.

When this study was published

Published in 2011. This review has been widely cited and updated systematic reviews have been conducted since.

The bigger picture

This review was widely cited in clinical guidelines and policy decisions regarding medical cannabis for chronic pain, establishing the evidence base for this indication.

Questions still open

Which specific cannabinoid formulation is most effective for which pain condition? Are the analgesic effects maintained with long-term use?

Common questions

Do cannabinoids actually help with chronic pain?

This systematic review found 15 out of 18 high-quality clinical trials showed significant pain relief from various cannabinoid treatments compared to placebo. The effects were described as "modest" but consistent.

Are cannabinoid pain treatments safe?

Across 18 clinical trials, no serious adverse effects were reported. Side effects were typically mild to moderate (dizziness, drowsiness, dry mouth) and rarely caused people to stop treatment.

Read the original research

Cannabinoids for treatment of chronic non-cancer pain; a systematic review of randomized trials.

British journal of clinical pharmacology, 72(5), 735-44

View on PubMed ↗Publisher’s paper ↗

Citation

Lynch, Mary E; Campbell, Fiona. (2011). Cannabinoids for treatment of chronic non-cancer pain; a systematic review of randomized trials.. British journal of clinical pharmacology, 72(5), 735-44. https://doi.org/10.1111/j.1365-2125.2011.03970.x