A review of reviews found cannabinoids may have modest effects on MS pain and spasticity, but evidence for other symptoms is lacking | Research

The takeaway

A systematic review of 11 prior reviews (covering 32 studies including 10 moderate-to-high quality RCTs) found that five reviews concluded cannabinoids may be effective for pain and/or spasticity in multiple sclerosis, while evidence for other MS symptoms was insufficient.

Neurologists treating MS; MS patients considering cannabinoid therapy; clinical guideline developers.

5 of 11 reviews supported modest cannabinoid efficacy for MS pain and/or spasticity

What the researchers found

Researchers conducted a "review of reviews" to synthesize high-quality systematic reviews on cannabinoids for multiple sclerosis symptoms.

Eleven eligible systematic reviews were identified, providing data from 32 studies including 10 moderate-to-high quality RCTs.

Five reviews concluded there was sufficient evidence that cannabinoids may be effective for MS-related pain and/or spasticity.

Few reviews reported conclusions for other MS symptoms including disability/progression, bladder function, tremor/ataxia, or quality of life.

The authors noted that cannabinoid effects on pain and spasticity were "modest" rather than large, and identified a critical evidence gap: no studies compared cannabinoids to non-cannabinoid treatments, only to placebo.

Why it matters

This is the most comprehensive evidence synthesis on cannabinoids for MS, aggregating findings from 11 prior reviews. The consistent finding of modest benefit for pain and spasticity, combined with the absence of comparator studies, helps clinicians set realistic expectations with patients.

The numbers in context

11 systematic reviews, 32 primary studies, 10 moderate-to-high quality RCTs. 5 reviews supported efficacy for pain and/or spasticity. No non-cannabinoid comparator studies exist.

How the study worked

Systematic review of systematic reviews. Searched for high-quality reviews examining cannabinoids (nabiximols, nabilone, dronabinol, plant-based) for MS symptoms. 11 reviews included, covering 32 primary studies.

What this study cannot tell us

Review of reviews inherits limitations of underlying reviews and primary studies. "Modest" effects are not precisely quantified across all reviews. Different reviews used different inclusion criteria and quality assessments.

How to read the evidence

Strong. Highest-level evidence synthesis (review of reviews) drawing on multiple systematic reviews and RCTs.

When this study was published

Published in 2018. Cannabinoid research for MS has continued, but head-to-head trials with non-cannabinoid comparators remain rare.

The bigger picture

The absence of head-to-head comparisons with existing MS treatments is a critical gap. Patients and clinicians cannot make informed choices between cannabinoids and conventional therapies without such data.

Questions still open

How do cannabinoids compare to baclofen for spasticity or gabapentin for neuropathic pain in MS? Are modest cannabinoid effects clinically meaningful to patients? Would specific MS subtypes respond better to cannabinoids?

Common questions

Do cannabinoids help with MS?

The evidence supports modest benefits for two MS symptoms: pain and spasticity. For other symptoms like disability progression, bladder function, or tremor, the evidence is insufficient to draw conclusions.

Why are the effects called "modest"?

While cannabinoids showed statistically significant benefits compared to placebo, the size of the improvements was relatively small. Some patients may experience meaningful relief, but cannabinoids are not a dramatic treatment for MS symptoms.

Read the original research

The Use of Cannabis and Cannabinoids in Treating Symptoms of Multiple Sclerosis: a Systematic Review of Reviews.

Current neurology and neuroscience reports, 18(2), 8

View on PubMed ↗Publisher’s paper ↗

Citation

Nielsen, Suzanne; Germanos, Rada; Weier, Megan; Pollard, John; Degenhardt, Louisa; Hall, Wayne; Buckley, Nicholas; Farrell, Michael. (2018). The Use of Cannabis and Cannabinoids in Treating Symptoms of Multiple Sclerosis: a Systematic Review of Reviews.. Current neurology and neuroscience reports, 18(2), 8. https://doi.org/10.1007/s11910-018-0814-x