Fibromyalgia and Medical Cannabis

Fibromyalgia is a disorder of chronic pain which affects somewhere between 1.8 million and 2.9 million people in the UK. It is a subjective condition with no clear understanding of the triggers or pathology and with no objective signs or diagnostic tests. Typically, fibromyalgia remains misdiagnosed for many years once symptoms emerge in a patient making management challenging for both patients and doctors alike.


The American College of Rheumatology has produced classification criteria for fibromyalgia and features include:

  • Widespread pain involving both sides of the body, above and below the waist as well as the axial skeletal system, for at least three months; AND

  • The presence of 11 tender points among the nine pairs of specified sites (18 points)

Patients with fibromyalgia often suffer a range of physical and psychological symptoms which include:

  • wide spread, chronic pain

  • tender or overly sensitive joints and muscle

  • extreme tiredness

  • forgetfulness or poor concentration

  • stress, worry or low mood

  • tingling, numbness or swelling of hands and feet

  • headaches

  • restless legs syndrome

  • irritability, depression

  • lower urinary symptoms

  • painful menstrual periods

  • irritable bowel syndrome (IBS)

  • high impact on work ability

What are the treatment options for fibromyalgia?

Current guidance suggest a range of treatments including CBT, moderate-intensity supervised aerobic exercise, psychological therapies and drug treatments which include antidepressants and opioids to reduce pain and improve function.

What are the challenges and limitations of treatments?

The main challenge is that patients often remain resistant to treatments and there are no standardised treatments that currently exist. The complex interplay of the social and psychological factors in the pathophysiology and symptomology of fibromyalgia make it very difficult to manage, particularly within the constraints of 10-minute NHS GP appointments.

Patients referred to secondary care (such as rheumatology or pain clinics) may wait months on end to be seen, often with poor outcomes.


Current pharmaceutical therapies appear to consistently let down patients who suffer with this condition and the reality is that many patients are inappropriately prescribed medications that are neither effective, safe nor licensed for use in fibromyalgia.

Cannabis based medicines for Fibromyalgia

Cannabis or cannabinoids have been frequently utilised by fibromyalgia patients to treat its complex, overlapping symptoms and there is now an emerging evidence base on these treatments.

This Dutch randomised placebo-controlled 4-way crossover study looked for pain-blocking effects of inhaled pharmaceutical-grade cannabis in 20 chronic pain patients with fibromyalgia. Cannabis varieties containing THC were demonstrated to have analgesic properties and produced a significant increase in pressure pain threshold relative to placebo (P < 0.01).

In a study of 56 patients with fibromyalgia (28 medical cannabis users versus 28 not using), medical cannabis showed a statistically significant (p<0.001) reduction of pain and stiffness, enhancement of relaxation, and an increase in somnolence and feeling of wellbeing. The mental health component summary score of the SF-36 was significantly higher (p<0.05) in medical cannabis users than in non-users.


A prospective observational study followed 367 fibromyalgia patients for a 6-month period after starting medical cannabis in a specialised medical cannabis clinic in Israel. The researchers assessed patients with questionnaires multiple times over the 6 months and had patients rate symptoms and report any side effects. Overall treatment success was achieved in 81% of patients (the proportion of patients reporting at least moderate overall improvement in their condition). Overall pain intensity reduced from a median of 9/10 to 5/10.  Around 20% of patients taking opioids or benzodiazepine were able to stop or reduce with the aid of medical cannabis. This real-world study allowed for patients to try several different strains and titrate their dosages according to individual needs demonstrated medical cannabis to be a safe and effective alternative for the treatment of fibromyalgia symptoms in a large cohort with 6-month follow up. These types of longitudinal / cohort studies have the benefit of the assessing multiple effects over time in individual patients.


In this study of 26 patients, medical cannabis treatment had a significant favourable effect on patients with fibromyalgia, with few adverse effects. After commencing medical cannabis treatment, all the patients reported a significant improvement in every parameter on the questionnaire, and 13 patients (50%) stopped taking any other medications for fibromyalgia. Eight patients (30%) experienced very mild adverse effects.

Endocannabinoid Deficiency Theory

Clinical endocannabinoid deficiency (CED) is a theory first coined in 2001 which hypothesises that a deficiency of endocannabinoids could explain the underlying pathophysiology for a number of conditions including migraines, irritable bowel syndrome and fibromyalgia.

All humans possess an underlying endocannabinoid tone that reflects levels of anandamide (AEA) and 2-arachidonoylglycerol (2-AG), the centrally acting endocannabinoids, their synthesis, catabolism, and the relative density of cannabinoid receptors in the brain. If endocannabinoid function is decreased, it follows that an individual may have lowered pain threshold, along with disruption of digestion, mood, and sleep - physiological systems all sub served by the endocannabinoid system. The theory of CED was based on the concept that many brain disorders are associated with neurotransmitter deficiencies. For example, acetylcholine in Alzheimer's disease, dopamine in parkinsonian syndromes and serotonin and norepinephrine in depression.


The future

There appears to be widespread dissatisfaction for both patients and professionals in the current approach to management of fibromyalgia. Emerging studies are demonstrating cannabis-based medicines as effective treatments that can help improve a wide range of symptoms for patients with fibromyalgia, playing an important role in improving and restoring homeostasis and general balance and overall quality of life. There is clearly now an urgent need to re-evaluate the management of this condition as a whole and focus on further larger studies of cannabis based medicines carried out in real time, to build out more robust evidence on efficacy, dosing and safety.

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DISCLAIMER:  All views are those of The Primary Care Cannabis Network. Information on this site is written for the purpose of general education. Information is not specific to any specific medical case and should not be taken to provide a diagnosis or treatment. This material should not be reproduced without the specific permission of the The Primary Care Cannabis Network. The opinions expressed here are of our society and do not necessarily represent the views of any other institutions of which members are affiliated with. The Primary Care Cannabis Network takes no responsibility for any actions taken by individuals in response to the information given here.

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