THC increases quality of life in patients with fibromyalgia, demonstrated by double-blind RCT

A randomised, double-blind, placebo-controlled clinical trial set out to determine the benefit of a tetrahydrocannabinol (THC)-rich cannabis extract on symptoms and quality of life of fibromyalgia patients.


Fibromyalgia is a reasonably common, long-term condition that affects the bones and muscles.

Objective: To determine the benefit of a tetrahydrocannabinol (THC)-rich cannabis oil on symptoms and quality of life of fibromyalgia patients.

Methods: A double-blind, randomised, placebo-controlled clinical trial was conducted for eight weeks to determine the benefit of a THC-rich cannabis oil (24.44 mg/mL of THC and 0.51 mg/mL of cannabidiol (CBD]) on symptoms and quality of life of 17 women with fibromyalgia, residents of a neighborhood with a lower socioeconomic profile in the city of Florianopolis, Brazil. The initial dose was one drop (∼1.22 mg of THC and 0.02 mg of CBD) a day with subsequent increases according to symptoms. The Fibromyalgia Impact Questionnaire (FIQ) was applied at pre- and postintervention moments and in five visits over eight weeks.

Results: There were no significant differences on baseline FIQ score between groups. However, after the intervention, the cannabis group presented a significant decrease in FIQ score in comparison with the placebo group (P = 0.005) and in comparison with cannabis group baseline score. (P < 0.001). Analyzing isolated items on the FIQ, the cannabis group presented significant improvement on the "feel good," "pain," "do work," and "fatigue" scores. The placebo group presented significant improvement on the "depression" score after intervention. There were no intolerable adverse effects.

Conclusions: Phytocannabinoids can be a low-cost and well-tolerated therapy to reduce symptoms and increase the quality of life of patients with fibromyalgia. Future studies are still needed to assess long-term benefits, and studies with different varieties of cannabinoids associated with a washout period must be done to enhance our knowledge of cannabis action in this health condition.

Keywords: Cannabis; Chronic Pain; Fibromyalgia; Marijuana; Pain; Tetrahydrocannabinol.



Trial profile


© The Author(s) 2020.

Published by Oxford University Press on behalf of the American Academy of Pain Medicine.


Published in PubMed.gov

Carolina Chaves 1, Paulo Cesar T Bittencourt 2, Andreia Pelegrini 3

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