Fibromyalgia is a chronic pain condition that can have a significant impact on the quality of life of patients. According to the NHS, fibromyalgia may affect almost 1 in 20 people in the UK, with women in their middle-age being more likely to develop the condition.
Although research suggests that fibromyalgia may be linked to changes in the way the central nervous system processes pain messages, the exact cause of the condition remains unknown. This means that there is no cure, and treatment options are focused on symptom management such as increased sensitivity to pain, fatigue, fogginess and problems with memory and concentration, muscle stiffness, and headaches.
Treatment options for fibromyalgia can include medicines such as antidepressants and painkillers as well as talking therapies and lifestyle changes. However, the need for more effective treatment options for fibromyalgia, as well as for other chronic pain conditions, is at an all-time high, as the risk of addiction and diminishing efficacy of opioid-based medications becomes increasingly recognised.
Cannabinoids and Fibromyalgia
As the need for alternative treatment options for chronic pain conditions becomes increasingly necessary, research into medical cannabis and cannabinoid-based preparations has been on the rise. A number of studies have now assessed the potential of cannabinoids in chronic pain conditions, including fibromyalgia.
Phyto-cannabinoids are derived from the cannabis plant and interact with the human body’s endocannabinoid system (ECS) – a network of receptors and endocannabinoids that are expressed throughout the central nervous system and immune system. The ECS has been found to have important neuro-modulatory roles such as in mood and temperature, and pain and appetite regulation.
Some research has suggested that some conditions, such as migraine, irritable bowel syndrome, and fibromyalgia, may be linked to a “clinical deficiency of the endocannabinoid system”, prompting further study into the benefits of cannabinoid-based medications.
A recently published review assessed the current literature on the efficacy of cannabinoids in fibromyalgia. The studies included in the review evaluated the “possible influence of cannabis on pain control in patients with fibromyalgia, with positive effects on quality of life and sleep”.
Current Literature on Cannabinoids and Fibromyalgia
The researchers identified 110 references, including abstracts of systematic reviews, meta-analyses, case reports, review articles and clinical trials. A total of 50 of the most relevant sources were included in this review.
The researchers identified a general trend in clinical trials that cannabis influenced pain in fibromyalgia patients and had positive effects on quality of life and sleep. For example, in one clinical trial, where 11 patients with fibromyalgia were given a 2.5mg – 15mg dose of THC per day, all patients who completed the trial experienced over 50% pain relief. However, it is noted that five patients withdrew from the trial early due to side effects including sedation, fatigue, and tiredness.
Further, a randomised, double-blind, placebo controlled clinical trial with 40 patients given nabilone at 0.5mg and 1mg twice a day, revealed that patients experienced a significant reduction in the Visual Analogue Scale (VAS) for pain, as well as in the Fibromyalgia Impact Questionnaire (FIQR).
One study also assessed the experiences of 367 patients who were given 670mg of medical cannabis per day followed by 1000mg per day. Almost two-thirds (211) patients reported a reduction in mean pain from 9 points to 5. Another study included in the review collected data via an online questionnaire of 383 patients using medical cannabis. The results revealed that 94% of respondents reported improved pain and 93% reported improved sleep. However, these results may have limitations due to the study design and methods used.
Researchers also assessed several systematic reviews which included trials in patients with chronic pain conditions, including fibromyalgia. One review included 107 trials in chronic pain – 7 of which were focused on fibromyalgia. These trials demonstrated that medical cannabis and nabilone (a synthetic tetrahydrocannabinol analogue) in comparison to placebo. This review showed that, although the effect on pain was minimal, it was significant and adverse effects were largely marginal.
Furthermore, various other systematic reviews of 20 controlled, randomised clinical trials found a “significant effect of cannabis and its derivatives on pain and sleep”. However, a review of four more clinical trials, cannabinoids failed to demonstrate a significant effect on pain management but were seen to improve quality of life and anxiety in patients with fibromyalgia.
A significant number of studies, including research in animal models of pain, have shown that cannabis and its derivatives have an effect on pain modulation which may be dose-dependent. While these pre-clinical trials don’t focus on specific diseases, such as fibromyalgia, they do focus on a set of symptoms and signs that exist in a number of chronic pain conditions.
However, the authors of this review acknowledge that relative “lack of available literature and the difficulty this represents to generalise both the positive and negative effects of medical cannabis for pain management, insomnia, anxiety and mood disorders” associated with fibromyalgia. Despite these difficulties, as well as the difficulty to make strong recommendations for the use of cannabinoids for the treatment of fibromyalgia based on these current findings, the researchers acknowledge the potential usefulness of these compounds in future developments.
Based on the available literature, the authors of this review maintain that more clinical evidence should be gathered in this area in order to fully support the routine use of cannabinoid-based medicines for the treatment of fibromyalgia.