Table of Contents
Clinical Takeaway
In this randomized controlled trial, CBD did not demonstrate superior pain relief compared to placebo in patients with fibromyalgia. The findings add to the limited evidence base and suggest that CBD should not yet be recommended as a reliable treatment for fibromyalgia pain.
#11 Cannabidiol versus placebo in patients with fibromyalgia: a randomised, double-blind, placebo-controlled, parallel-group, single-centre trial.
Citation: Rasmussen Marianne Uggen et al.. Cannabidiol versus placebo in patients with fibromyalgia: a randomised, double-blind, placebo-controlled, parallel-group, single-centre trial.. Annals of the rheumatic diseases. 2026. PMID: 40846590.
Design: 5 Journal: 0 N: 2 Recency: 3 Pop: 2 Human: 1 Risk: -2
- Preclinical only
Abstract: OBJECTIVES: Cannabidiol (CBD) is used to alleviate fibromyalgia pain despite limited evidence for efficacy. This study assessed the efficacy and safety of CBD vs placebo in patients with fibromyalgia, hypothesising that CBD would be superior to placebo in reducing pain. METHODS: In this single-centre, double-blind, randomised, placebo-controlled trial, patients diagnosed with fibromyalgia were recruited from a specialised outpatient clinic in Denmark. Eligible participants were randomised 1:1 and stratified by sex, defined as biological sex assigned at birth based on physical anatomy. Age (<45 vs ≥45), and pain level (<7 vs ≥7) on a 0 to 10 numeric rating scale (NRS) to receive 50 mg plant-derived CBD or placebo tablets. The primary outcome was change in pain intensity at week 24, assessed on the NRS pain subitem in the revised Fibromyalgia Impact Questionnaire in the intention-to-treat population. Adverse events were monitored throughout the study in the safety population. RESULTS: Of 273 participants screened for eligibility, 200 were included and randomised to receive CBD (n = 100) or placebo (n = 100). At week 24, mean change in pain intensity was -0.4 points (95% CI: -0.82 to 0.08) in the CBD group and -1.1 points (95% CI: -1.53 to -0.63) in the placebo group, corresponding to a between-group difference of -0.7 points (95% CI: -1.2 to -0.25; P = .0028) favouring placebo. Adverse events were generally mild and evenly distributed between groups. CONCLUSIONS: The findings do not support CBD 50 mg daily as an analgesic supplement for patients with fibromyalgia. CLINICALTRIALS: gov number: NCT04729179.
What This Study Teaches Us
In this well-designed 24-week trial, 50 mg daily CBD was no better than placebo for fibromyalgia pain, and placebo actually showed numerically greater improvement. This directly challenges the common clinical assumption that CBD is an effective analgesic for fibromyalgia.
Why This Matters Clinically
Many patients with fibromyalgia are currently using or asking about CBD as an alternative to conventional analgesics. Clinicians need evidence to guide these conversations honestly, and this study provides the kind of head-to-head comparison that was previously lacking. Without clear efficacy data, we should reconsider how we position CBD in fibromyalgia management.
Study Snapshot
| Study Design | Randomized, double-blind, placebo-controlled, parallel-group trial at a single specialized outpatient clinic |
| Population | 200 patients with fibromyalgia (100 per arm), stratified by sex, age (split at 45 years), and baseline pain severity (NRS split at 7) |
| Intervention | 50 mg plant-derived CBD tablet daily versus placebo for 24 weeks |
| Primary Outcome | Change in pain intensity at week 24 on the 0-10 numeric rating scale (NRS) from the Revised Fibromyalgia Impact Questionnaire |
| Key Result | CBD group improved 0.4 points; placebo group improved 1.1 points. Placebo was 0.7 points superior (95% CI: -1.2 to -0.25; P=0.0028) |
Where This Paper Deserves Skepticism
The study is single-center and recruited from a specialized Danish clinic, which may limit generalizability to broader fibromyalgia populations. The 50 mg dose is relatively conservative and may not represent what patients typically self-dose or what proponents might argue is a therapeutic range. The abstract does not report adherence rates, baseline characteristics by group, or subgroup analyses that might identify responders. The strong placebo response (1.1-point improvement) is noteworthy but typical for pain studies in fibromyalgia and does not explain away the finding.
Dr. Caplan’s Take
This is a credible negative trial that deserves weight in my practice. I’ve seen CBD marketed aggressively for fibromyalgia pain, and this randomized evidence suggests that belief in the mechanism (endocannabinoid deficiency, CB1/CB2 modulation) has outpaced actual clinical benefit. I won’t say CBD has no role in fibromyalgia management, but I can no longer present it as a supported analgesic option without acknowledging this trial. Patients deserve to know that the evidence doesn’t support its use for pain reduction specifically.
Clinical Bottom Line
CBD 50 mg daily does not improve fibromyalgia pain better than placebo and may perform worse. Clinicians should not recommend CBD as a primary analgesic for fibromyalgia until stronger evidence emerges.
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