Is a Low Dosage of Medical Cannabis Effective for Treating Pain Related to Fibromyalgia? A Pilot Study and Systematic Review

Background and Objectives: Fibromyalgia is a multifaceted and frequently misunderstood chronic pain disease marked by widespread musculoskeletal pain and cognitive/somatic dysfunction. This trial aims to contribute to the existing knowledge on treating fibromyalgia (FM) with medical cannabis (Cannabis sativa L.) and explore a safer and more effective cannabis administration method. The goal is to provide evidence-based findings that can guide alternative treatment options for FM patients by assessing a pilot study. Materials and Methods: The trial was performed at the pain therapy unit of the San Carlo Hospital (Potenza, Italy) by administrating to 30 FM patients 100 mg/day of Bedrocan^® as a decoction. The Numerical Rating Scale (NRS) and SF-12 short-form health questionnaire were used to evaluate pain intensity and the quality of life at the beginning of the study and the 6th-month follow-up. A systematic review of all clinical studies investigating the use of cannabis to reduce FM was also undertaken to place this study in the context of the existing evidence base. Results: Pain intensity evaluated with the NRS lowered from a median of 8 [95% CI 7.66–8.54] at a baseline to a median of 4 (95% CI 3.28–4.79) after 6 months of follow-up (p-value < 0.001; t-Test). Similarly, significant physical and mental state improvement, evaluated with the SF-12 questionnaire, was found in 96.67% and 82.33% of patients, respectively (95% CI 44.11–51.13 for the physical state, and 53.48–58.69 for mental state assessed after the 6th-month follow-up; p-value < 0.001; t-Test). The systematic analysis of the literature identified 10 clinical trials concerning the treatment of fibromyalgia with cannabis. Conclusions: Considering results from the present pilot study and systematic review, it is possible to assume that medical cannabis may be considered an alternative therapy for FM patients who do not respond to conventional pharmacological therapy.