Medical cannabis improved pain in fibromyalgia patients who failed other treatments | Research

The takeaway

In 38 fibromyalgia patients resistant to conventional therapy, medical cannabis significantly improved pain and disability scores, though nearly half discontinued due to non-serious side effects like mental confusion.

Fibromyalgia patients, pain management clinicians, and anyone interested in medical cannabis for chronic pain conditions.

48.6% discontinued due to side effects, mostly mental confusion

What the researchers found

Significant improvements (P < 0.01) were observed in pain scores (NRS), disability (ODI), widespread pain (WPI), and symptom severity (SyS) at various time points up to 12 months. However, 17 patients (48.6%) discontinued due to non-serious adverse effects including mental confusion (37%), dizziness (14%), nausea/vomiting (14%), and restlessness (14%).

Why it matters

Fibromyalgia is notoriously difficult to treat, and patients who fail conventional therapy have few options. This series provides real-world data on both the potential benefits and the significant tolerability challenges of medical cannabis in this population.

The numbers in context

38 patients; 30 at 1 month, 18 at 3 months, 12 at 12 months; 48.6% discontinued due to AEs; mental confusion 37%; median THC dose 46.2 mg (dominant) or 23.6 mg THC + 38 mg CBD (hybrid) at 3 months

How the study worked

Retrospective, open-label case series of 38 fibromyalgia patients resistant to conventional therapy at an Italian pain clinic. Patients received licensed medical cannabis as powdered flowers or oil extracts with various THC/CBD ratios. Outcomes measured at 1, 3, and 12 months.

What this study cannot tell us

No control group or blinding. High dropout rate limits interpretation of long-term results. Retrospective design. Small sample. Italian regulatory context may affect product availability and dosing.

How to read the evidence

Small open-label case series without a control group, though it provides real-world data on a treatment-resistant population.

When this study was published

Published in 2021.

The bigger picture

The tension between meaningful symptom improvement and a nearly 50% dropout rate due to side effects highlights the challenge of medical cannabis for fibromyalgia. Finding the right dosing and formulation to maximize benefit while minimizing cognitive side effects remains critical.

Questions still open

Would lower doses or different THC:CBD ratios reduce the dropout rate while preserving benefits? Are the patients who tolerated cannabis long-term fundamentally different from those who dropped out? How does this compare to other treatments for treatment-resistant fibromyalgia?

Common questions

How effective was medical cannabis for fibromyalgia?

Pain and disability scores improved significantly in patients who stayed on treatment. However, nearly half of patients stopped due to side effects, so the benefits may be limited to those who can tolerate the medication.

What were the most common side effects?

Mental confusion was the most common at 37%, followed by dizziness (14%), nausea/vomiting (14%), and restlessness/irritation (14%). All were classified as non-serious.

Read the original research

Medical cannabis for the treatment of fibromyalgia syndrome: a retrospective, open-label case series.

Journal of cannabis research, 3(1), 4

View on PubMed ↗Publisher’s paper ↗

Citation

Mazza, Manuela. (2021). Medical cannabis for the treatment of fibromyalgia syndrome: a retrospective, open-label case series.. Journal of cannabis research, 3(1), 4. https://doi.org/10.1186/s42238-021-00060-6