Cochrane Review Found No Convincing Evidence That Cannabinoids Help Fibromyalgia | Research

The takeaway

A Cochrane systematic review found only two small studies (72 total participants) testing cannabinoids for fibromyalgia, with very low quality evidence and no convincing support for their use.

Read this if you have fibromyalgia and use or are considering cannabinoids for symptom management.

Only 72 patients have been studied in RCTs of cannabinoids for fibromyalgia, with very low quality evidence.

What the researchers found

The Cochrane Collaboration, considered the gold standard for medical evidence review, found only two randomized controlled trials testing cannabinoids for fibromyalgia, with a combined total of just 72 participants. Both studies tested nabilone (a synthetic cannabinoid) at 1 mg/day.

No study reported the proportion of participants achieving meaningful pain relief (30% or 50% reduction) or significant improvement. All evidence was rated as very low quality due to indirectness, imprecision, and potential reporting bias.

Third-tier (very low quality) evidence suggested nabilone might be slightly better than placebo for pain and quality of life, and slightly better than amitriptyline for sleep. But the differences were modest and the evidence was insufficient for any clinical recommendation.

No studies were found testing herbal cannabis, plant-based cannabinoids, or any synthetic cannabinoid other than nabilone for fibromyalgia.

Why it matters

Fibromyalgia patients are among the most common medical cannabis users, yet this Cochrane review reveals that the evidence supporting this use is almost nonexistent. Only 72 total patients have been studied in controlled trials, and the evidence quality is very low. This represents a massive gap between patient behavior and scientific evidence.

The numbers in context

2 RCTs included. 72 total participants (studies of 32 and 40). Both tested nabilone 1 mg/day at bedtime. Study durations: 4 and 6 weeks. Very low quality evidence overall. No studies of herbal cannabis or other cannabinoids found.

How the study worked

Cochrane systematic review searching CENTRAL, MEDLINE, and EMBASE through April 2016, plus clinical trial registries and author contact. Included RCTs of at least 4 weeks using any cannabis formulation for adults with fibromyalgia. Used three-tier evidence hierarchy and GRADE assessment.

What this study cannot tell us

The review is limited by the scarcity of available trials rather than by its own methodology. Only two small studies existed. Both used nabilone specifically, which may not represent the effects of other cannabinoids or whole-plant cannabis. The short study durations (4-6 weeks) may not capture long-term effects.

How to read the evidence

Moderate evidence assessment quality (Cochrane methodology is rigorous), but the underlying evidence it reviews is very low quality due to the scarcity and small size of available trials.

When this study was published

Published in 2016. Some additional studies of cannabinoids for fibromyalgia have since been conducted.

The bigger picture

Cannabis is widely used for fibromyalgia based on patient reports, theoretical rationale (endocannabinoid deficiency hypothesis), and limited observational data. But the randomized trial evidence is almost completely absent. This Cochrane review highlights the urgent need for well-designed clinical trials, given how many patients are already using cannabinoids for this condition.

Questions still open

Why have so few clinical trials been conducted given the widespread use of cannabis for fibromyalgia? Would whole-plant cannabis or CBD-dominant products show different results than nabilone? Does the endocannabinoid deficiency hypothesis support a stronger rationale for cannabinoids in fibromyalgia than the trial data currently shows?

Common questions

Does cannabis help fibromyalgia?

Many fibromyalgia patients report benefit, but as of this Cochrane review, only 72 patients had been studied in controlled trials, and the evidence was rated very low quality. There is currently no convincing clinical trial evidence supporting this use.

Why is the evidence so poor?

Very few randomized controlled trials have been conducted. Both existing studies tested only nabilone (a synthetic cannabinoid) in small groups for short periods. No studies of herbal cannabis or CBD products for fibromyalgia were found. The legal status of cannabis has historically made research difficult.

Read the original research

Cannabinoids for fibromyalgia.

The Cochrane database of systematic reviews, 7(7), CD011694

View on PubMed ↗Publisher’s paper ↗

Citation

Walitt, Brian; Klose, Petra; Fitzcharles, Mary-Ann; Phillips, Tudor; Häuser, Winfried. (2016). Cannabinoids for fibromyalgia.. The Cochrane database of systematic reviews, 7(7), CD011694. https://doi.org/10.1002/14651858.CD011694.pub2