Nearly 500 fibromyalgia patients in the UK saw improvements in pain, anxiety, and sleep after starting medical cannabis | Research

The takeaway

A registry study of 497 fibromyalgia patients found that cannabis-based medicinal products were associated with improvements in pain, anxiety, sleep, and quality of life over up to 18 months, though adverse events were common.

Fibromyalgia patients, pain management clinicians, medical cannabis researchers

497 fibromyalgia patients showed improvement across all outcome measures over 18 months

What the researchers found

All patient-reported outcome measures improved significantly from baseline through 18 months of follow-up. Higher daily CBD doses (above 25 mg) and previous cannabis experience were linked to better fibromyalgia-specific outcomes. However, 45.67% of patients reported adverse events, mostly mild-to-moderate, with fatigue being the most common.

Why it matters

Fibromyalgia is notoriously difficult to treat, with many patients finding conventional therapies inadequate. This is one of the largest real-world datasets on medical cannabis for fibromyalgia, providing evidence that may inform clinical decisions.

The numbers in context

497 patients; mean age 44.66 years; 68.61% female; 53.92% unemployed; CBD doses above 25 mg/day associated with better outcomes (p < 0.050); 45.67% reported adverse events; 2,100 total AEs; 85.33% mild-to-moderate; fatigue most common AE (30.78%)

How the study worked

Case series from the UK Medical Cannabis Registry (UKMCR) analyzing 497 patients prescribed cannabis-based medicinal products for fibromyalgia. Outcomes measured at 1, 3, 6, 12, and 18 months using validated scales for symptom severity, widespread pain, quality of life, anxiety, and sleep.

What this study cannot tell us

No control group or randomization. Registry-based data subject to selection bias. Patients self-selected for treatment. High dropout rates likely at later follow-up points. Cannot distinguish cannabis effects from placebo or natural disease fluctuation.

How to read the evidence

Moderate: large real-world sample with validated outcome measures and extended follow-up, but no control group and observational design.

When this study was published

2026 publication from the UK Medical Cannabis Registry.

The bigger picture

This adds to growing real-world evidence from medical cannabis registries worldwide. The high adverse event rate compared to other UKMCR patient groups may reflect fibromyalgia-specific sensitivity, possibly related to the central sensitization that characterizes the condition.

Questions still open

Why do fibromyalgia patients report more adverse events than other medical cannabis users? Does the central sensitization mechanism make these patients more sensitive to cannabinoid side effects? Would randomized controlled trials confirm these observational findings?

Common questions

What symptoms improved with medical cannabis for fibromyalgia?

Patients showed statistically significant improvements in fibromyalgia symptom severity, widespread pain, general quality of life, anxiety, and sleep quality.

Were there common side effects?

Yes, 45.67% of patients reported adverse events, totaling 2,100 events. Most (85.33%) were mild-to-moderate, with fatigue being the most common at 30.78%.

Read the original research

UK Medical Cannabis Registry: a case series analysing clinical outcomes of medicinal cannabis therapy for fibromyalgia.

Clinical rheumatology, 45(3), 1927-1938

View on PubMed ↗Publisher’s paper ↗

Citation

Varadpande, Madhur; Erridge, Simon; Aggarwal, Arushika; Clarke, Evonne; McLachlan, Katy; Coomber, Ross; Barnes, Shelley; Darweish Medniuk, Alia; Guru, Rahul; Holden, Wendy; Sajad, Mohammed; Searle, Robert; Usmani, Azfer; Varma, Sanjay; Rucker, James J; Platt, Michael; Sodergren, Mikael H. (2026). UK Medical Cannabis Registry: a case series analysing clinical outcomes of medicinal cannabis therapy for fibromyalgia.. Clinical rheumatology, 45(3), 1927-1938. https://doi.org/10.1007/s10067-025-07846-6