Review Confirms Very Limited Evidence for Cannabinoids in Rheumatic Disease Pain | Research

The takeaway

A systematic review of four trials with just 203 patients found that cannabinoids showed some pain and sleep benefits in rheumatic conditions, but nearly half of patients experienced side effects like dizziness and drowsiness.

Read this if you have arthritis or fibromyalgia and want an honest look at the evidence for cannabis-based treatments.

Nearly 50% of patients reported dizziness, cognitive problems, or drowsiness

What the researchers found

This review identified the same thin evidence base for cannabinoids in rheumatic diseases: four short studies totaling only 203 patients across rheumatoid arthritis, fibromyalgia, and osteoarthritis.

Cannabinoids had a statistically significant effect on pain in two of the studies and on sleep in two studies. Quality of life improved in one study. However, the osteoarthritis trial was terminated early because the treatment was not working.

The side effect profile was notable. Dizziness, cognitive problems, drowsiness, and nausea were reported by nearly half of patients. No serious adverse events occurred during the short study durations.

Why it matters

This review from a different research group confirms the same conclusion as RTHC-01154: the evidence base for cannabinoids in rheumatic pain is extremely thin. The additional detail on side effects (affecting nearly half of patients) and the failed osteoarthritis trial provide important counterweights to the narrative that cannabinoids are universally helpful for pain.

The numbers in context

203 total patients across four studies. Pain significant in 2/4 studies. Sleep significant in 2/4 studies. Quality of life improved in 1/4. OA trial terminated for futility. Dizziness, cognitive problems, drowsiness, and nausea in nearly 50% of patients. All three completed studies had high risk of bias.

How the study worked

Systematic search of Medline, Embase, and CENTRAL databases. Included randomized controlled trials comparing cannabinoids (phyto- and synthetic) with any control for rheumatic disease pain. Assessed efficacy (pain, sleep, quality of life), tolerability (dropout rates), and safety (serious adverse events). All three completed studies had high risk of bias.

What this study cannot tell us

Extremely small combined sample size (203 patients). Short study durations. High risk of bias in all completed studies. No studies of herbal cannabis. Heterogeneous conditions and products limit comparison.

How to read the evidence

Rigorous systematic review methodology, but the underlying evidence consists of only four small, short, high-bias trials.

When this study was published

Published in 2016. Additional trials may have been conducted since, but the evidence gap highlighted here was significant.

The bigger picture

Having two independent systematic reviews reach the same conclusion in the same year strengthens the finding that evidence is insufficient. The osteoarthritis trial failure and the high rate of cognitive side effects are particularly important for the millions of older adults with OA who might consider cannabinoids.

Questions still open

Why did the osteoarthritis trial fail while others showed some benefit? Are the cognitive side effects dose-dependent, and would lower doses still provide pain relief? Would topical cannabinoid formulations avoid the systemic side effects?

Common questions

Can cannabinoids help with osteoarthritis?

The only osteoarthritis trial included in this review was terminated early because the treatment was not working, though studies in other rheumatic conditions showed some pain and sleep benefits.

What are the side effects of cannabinoids for pain?

Nearly half of patients in the reviewed trials experienced dizziness, cognitive problems, drowsiness, or nausea. No serious adverse events occurred during the short study periods.

Read the original research

Efficacy, Tolerability, and Safety of Cannabinoid Treatments in the Rheumatic Diseases: A Systematic Review of Randomized Controlled Trials.

Arthritis care & research, 68(5), 681-8

View on PubMed ↗Publisher’s paper ↗

Citation

Fitzcharles, Mary-Ann; Ste-Marie, Peter A; Häuser, Winfried; Clauw, Daniel J; Jamal, Shahin; Karsh, Jacob; Landry, Tara; Leclercq, Sharon; Mcdougall, Jason J; Shir, Yoram; Shojania, Kam; Walsh, Zach. (2016). Efficacy, Tolerability, and Safety of Cannabinoid Treatments in the Rheumatic Diseases: A Systematic Review of Randomized Controlled Trials.. Arthritis care & research, 68(5), 681-8. https://doi.org/10.1002/acr.22727