Clinical Takeaway
In this randomized, double-blind, placebo-controlled trial, CBD did not demonstrate superiority over placebo in reducing pain among patients with fibromyalgia. The findings add to a growing body of evidence that questions the assumption of meaningful clinical benefit from CBD alone for this condition. Patients and clinicians should weigh these results carefully when considering CBD as a treatment option for fibromyalgia-related pain.
#9 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
A 24-week trial of 50 mg daily CBD showed no benefit for fibromyalgia pain compared to placebo, and placebo actually performed numerically better. This directly contradicts the common clinical assumption that CBD is an effective pain treatment for this condition.
Why This Matters Clinically
Many patients with fibromyalgia are already using or asking about CBD as an alternative to conventional analgesics. This RCT provides rare head-to-head evidence that can inform shared decision-making and help clinicians counsel patients realistically about what the data actually shows.
Study Snapshot
| Study Design | Randomized, double-blind, placebo-controlled, single-center trial |
| Population | 200 patients with fibromyalgia (100 per group) recruited from a specialized outpatient clinic in Denmark; stratified by sex, age, and baseline pain severity |
| Intervention | 50 mg plant-derived CBD tablets daily versus placebo for 24 weeks |
| Primary Outcome | Change in pain intensity at week 24 on numeric rating scale (NRS) pain subitem of the revised Fibromyalgia Impact Questionnaire |
| Key Result | CBD group improved by 0.4 points; placebo group improved by 1.1 points on a 0-10 scale (p = 0.0028 favoring placebo, between-group difference of 0.7 points) |
Where This Paper Deserves Skepticism
The abstract does not report what percentage of participants completed the trial or whether there was differential dropout between arms, which matters for interpreting the results. The dose of 50 mg is fixed and relatively modest; we don’t know if higher doses were tested or why this particular dose was chosen. The study is single-center in Denmark, which may limit generalizability to other populations or healthcare systems. We lack detail on baseline characteristics, medication washout periods, or whether participants had prior CBD exposure.
Dr. Caplan’s Take
I read this with interest because we genuinely lack good evidence for or against CBD in fibromyalgia, and this is a properly designed RCT. What strikes me is not just that CBD didn’t beat placebo, but that placebo response was robust (1.1 point improvement) while CBD lagged noticeably behind. This suggests either that CBD at this dose has no signal in fibromyalgia pain, or that any benefit is swamped by placebo effect. My practice implication is straightforward: I can’t recommend CBD as an analgesic for fibromyalgia on this evidence, and I need to be honest with patients about that.
Clinical Bottom Line
CBD 50 mg daily did not reduce fibromyalgia pain more than placebo over 24 weeks. Clinicians should not position CBD as an evidence-based analgesic for fibromyalgia without better data.
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