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Cannabinoids and the endocannabinoid system in fibromyalgia: a review of preclinical and clinical research

Woman with neck pain with cannabis molecule next to her


Stephanie Bourke, Anne Schlag, Saoirse Elizabeth O’Sullivan, David Nutt, David Finn


May 21, 2022

Fibromyalgia affects millions of people worldwide and has a significant impact on quality of life. Fibromyalgia symptoms include persistent widespread pain, fatigue, stiffness, sleep disturbances and cognitive dysfunction. Endogenous cannabinoids (endocannabinoids), the body’s own marijuana-like transmitters, are involved in the regulation of many processes in the body, including pain. Cannabis sativa, has been cultivated and used for recreational and medicinal purposes for at least 5000 years. Cannabis contains more than a hundred plant-produced cannabinoids (phytocannabinoids). Phytocannabinoids are a diverse class of naturally occurring chemical compounds, some of which interact with, and mediate their effects via our endocannabinoid system. The most common and well-characterised phytocannabinoids are Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD).

Preclinical research has provided some evidence in support of the therapeutic potential of drugs that target the endocannabinoid system for the treatment of fibromyalgia-related symptoms.  Enhancing the endocannabinoid system by inhibiting enzymes (such as fatty acid amide hydrolase [FAAH]) that break down endocannabinoids, has been shown to ameliorate pain and anxiety-related behaviour.

There is a paucity of high-quality clinical trials of synthetic THC or cannabis extracts in patients with Fibromyalgia. However, surveys of patients who use whole-plant cannabis suggest that they benefit from the use of smoked or vaporised cannabis in terms of pain relief, reduced stiffness, relaxation, and quality of life. It is important to note that adverse effects from cannabinoids or cannabis in the majority of studies are common, but mild.

The limited number of randomised controlled clinical trials, small number of participants included in current studies and the paucity of studies investigating the long-term effects of cannabis treatment, are some of the limitations that preclude a recommendation for using cannabis or cannabinoids for the treatment of Fibromyalgia. Moreover, consistent and rigorous dosing regimens and identification of the most appropriate route of administration are required. Nonetheless, data from preclinical studies and promising patient reported outcomes indicate the potential for cannabinoid-based drugs for the treatment of Fibromyalgia.

Professor David Nutt and Dr. Anne Katrin Schlag of Drug Science have co-authored a narrative review manuscript on cannabinoids, the endocannabinoid system and fibromyalgia with Professor David Finn (NUI Galway, lead/corresponding author), Professor Saoirse O’Sullivan (CanPharmConsulting) and Stephanie Bourke (NUI Galway, first author).  The paper has been published recently in the journal Pharmacology and Therapeutics (Bourke et al., 2022). 

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