A Landmark Study from the UK
In the most extensive study of its kind in the United Kingdom, researchers have found that cannabis-based medicinal products (CBMPs) may help ease the chronic pain, anxiety, and sleep disturbances experienced by people living with fibromyalgia — a condition that affects an estimated 5% of adults, primarily women.
The study, published in Clinical Rheumatology, analysed real-world data from 497 fibromyalgia patients enrolled in the UK Medical Cannabis Registry. These patients were prescribed various formulations of CBD and THC-based treatments, including oils and inhaled dried flower, and followed for up to 18 months.
The results? Patients reported consistent improvements across several key symptoms — but also experienced a relatively high rate of side effects, many of which were mild but some severe.
What Is Fibromyalgia?
Fibromyalgia is a complex, long-term disorder defined by widespread musculoskeletal pain, often accompanied by fatigue, poor sleep, cognitive difficulties (“fibro fog”), and mental health conditions such as anxiety and depression. It is believed to stem from central sensitisation — a dysfunction in the way the nervous system processes pain signals.
Current treatments, including antidepressants and anticonvulsants like duloxetine, pregabalin, and amitriptyline, often have limited effectiveness and poor tolerability, leading many patients to discontinue use.
How the Study Was Conducted
Researchers included patients who had been on licensed fibromyalgia medications but failed to achieve adequate symptom relief. Participants were prescribed CBMPs — either orally (as oils, capsules, or lozenges) or via inhalation (vaporised dried flower). They completed patient-reported outcome measures (PROMs) at baseline and at 1, 3, 6, 12, and 18 months.
The PROMs measured:
- Pain intensity and distribution (Fibromyalgia Symptom Severity and Widespread Pain Index)
- Anxiety levels (GAD-7 scale)
- Quality of life (EQ-5D-5L)
- Sleep quality (Single-Item Sleep Quality Scale)
- Overall perceived change (Patient Global Impression of Change)
Promising Results Across Multiple Symptoms
At every follow-up interval, patients reported statistically significant improvements in all key symptom categories. For instance:
- Pain symptoms decreased the most in the first month and remained improved at 18 months, though with some decline.
- Anxiety scores dropped from an average of 9.68 to 8.41.
- Sleep quality, initially rated very low (3.42/10), rose to 4.32.
- Quality of life, as measured by the EQ-5D-5L, improved across all domains.
Patients prescribed higher doses of CBD (over 25 mg/day) and those who were current cannabis users before treatment were more likely to report improvements. The average THC dose increased dramatically over the course of the study, reflecting titration based on tolerance and response — from just 2 mg/day at baseline to over 112 mg/day at 18 months.
Side Effects: A Notable Trade-Off
The downside? Nearly 46% of patients reported a total of 2,100 adverse events (AEs) during the study. While 85% were mild to moderate, including fatigue, dry mouth, and concentration issues, 306 events were rated as severe, and 2 were life-threatening (anxiety and a lung infection).
Interestingly, patients aged 41–50, those with poorer sleep quality at baseline, and previous cannabis users were less likely to report adverse events.
A higher CBD dose was linked to an increased risk of side effects, particularly in patients with pre-existing anxiety.
Limitations and Considerations
While the results are promising, this was an observational study, not a randomised controlled trial (RCT). That means we cannot definitively conclude that CBMPs caused the improvements. Factors such as placebo effects, expectation bias, or ongoing lifestyle changes may have played a role.
Moreover, the fact that many participants were already cannabis users may suggest a selection bias — people who already respond well to cannabis may have been more likely to enroll. And since all data came from a private clinic, findings may not generalise to all populations.
Still, for patients with fibromyalgia who have exhausted other options, these real-world data offer hope — and a call for more rigorous clinical trials.
Related Reads on The Cannex
If you’re interested in medical cannabis and chronic pain, check out these related articles:
- Cannabis Oil Linked to Tumour Regression in Liver Cancer Case Study
- Inhaled Cannabis Offers Pain Relief for Diabetic Neuropathy
- THC and the Brain’s Pain Filter: New Fibromyalgia Study
- THC Beverages: Alcohol Alternative or Wellness Trend?
Frequently Asked Questions
What is CBD?
CBD, or cannabidiol, is a non-psychoactive compound found in cannabis. It has been studied for its potential to reduce pain, anxiety, and inflammation without causing a “high.”
What is THC?
THC (tetrahydrocannabinol) is the primary psychoactive component of cannabis. It interacts with brain receptors to alter mood, perception, and pain sensation.
What does “central sensitisation” mean?
Central sensitisation refers to the way the brain and spinal cord amplify pain signals. It is a key mechanism believed to underlie fibromyalgia, making the nervous system more sensitive to pain stimuli.
What are PROMs (Patient-Reported Outcome Measures)?
PROMs are standardized questionnaires used in research and clinical practice to assess patients’ perceptions of their health status, symptoms, and quality of life.
