Cannabis and fibromyalgia

Fibromyalgia is one of those disorders with an unknown cause but highly incapacitating symptoms. It is precisely because its etiopathogenesis (cause) is not known, plus the lack of specific effective treatment, that it has taken the medical community so long to recognise it as an illness.

An observational study carried out in Barcelona was published recently, in which the perceived benefits of self-medication with cannabis were evaluated in a group of women with this condition. This is one of those rare scientific studies where the results can be immediately clinically useful to patients and doctors alike.

It is thought that fibromyalgia is a disorder of neuropathic origin, i.e. that it is caused by a dysfunction of the nervous system.

Treatment with Cannabis

While there are different theories that attempt to go some way towards explaining its causes, today it is widely accepted that fibromyalgia is an illness of organic origin, with recognised physical causes, despite the fact that there are as yet no clinical markers on which to base a diagnosis, and that a diagnosis can only be given based on clinical manifestations from patients.

The theories to explain the causes range from a deregulation of neurotransmitters (principally dopamine and serotonin) to a dysfunction of the physiological mechanisms of stress regulation (what is known in medical jargon as the hypothalamic-pituitary-adrenal, or HPA axis).

Other theories base their explanations for the symptoms on a disruption to the immune system. Whatever the causes, it seems that treatment with cannabis fits in with every one of these theories given that, for example, we know that the endocannabinoid system is involved in physiological functions that include the regulation of the dopaminergic and serotonergic systems, the regulation of the physiological response to stress and on top of this, that the immune system is richly populated with CB2 receptors, which is why it can be highly influenced by cannabinoids, both endogenous and exogenous.

In fact, the main symptom of fibromyalgia is a very low pain threshold and the subjective feeling of pain is mediated, among others, by the three physiological processes mentioned, which is why, irrespective of what the causes may be, it makes sense to think that the treatment of fibromyalgia with cannabinoids could be a therapeutic option worth contemplating.

This is all the more so when you take into account the fact that other disorders that also involve neuropathic pain and that also have a disruption of the immune system as an etiological basis, such as multiple sclerosis, are treated with cannabinoids (Sativex, the first medicine based on cannabis extracts on the market, has recently been authorised in Spain for the treatment of multiple sclerosis). There is in fact a diverse group of functional clinical syndromes, in addition to fibromyalgia, for which no clear medical explanation has been found to date, such as migraines or irritable bowel syndrome, for which treatment with cannabis has proved helpful in some patients.

The investigator Ethan Russo has suggested as an explanation for this that the common cause of these disorders is rooted in a deregulation of the endocannabinoid system (, which seems the most plausible idea – even if it is only at this time another hypothesis to explain these clinical syndromes – given that they share a certain level of effectiveness of treatment with cannabis. Other symptoms inherent to fibromyalgia, apart from the pain – which is the main symptom – are chronic fatigue, morning stiffness, constant tiredness and affective disorders.

Fybromalgia tender points
Fybromalgia tender points

The study in question, conducted from the Municipal Institute of Medical Research in Barcelona, was published in the open-access scientific journal PloS One(

Studies and statistics on the topic

A total of 56 women participated in the study, with an average age of 50 years, all suffering from fibromyalgia, of which half (28) self-medicated with cannabis and the other half didn’t. All the women had a degree of illness between moderate and severe in accordance with the classification by the American College of Rheumatology. The women were recruited from fifteen different associations for patients afflicted with fibromyalgia and from a cannabis consumers’ club, all in Barcelona. Both groups were matched in terms of sociodemographic variables, clinical manifestations of the illness (type of symptoms suffered) and pharmacological treatments received, both allopathic and based on complementary medicine. 40% of the women in the cannabis group had a history of consumption of less than one year, 32% of between one and three years, and the remaining 29% of more than three years.

Only eight of the 28 women had consumed cannabis recreationally prior to suffering the illness. All of them consumed marihuana, 54% by smoking it, 46% by consuming it as food and 43% by combining both. Eleven women consumed it daily, five between twice and four times a week, three less than twice a week and eight only occasionally. One consumption meant between one and two marihuana cigarettes for the women who smoked it, or one spoonful when it was consumed in food.

Twelve women smoked one marihuana cigarette per day, five between two and three, and three, more than three a day. For the source of supply, fourteen women obtained the marihuana through family and friends, seven acquired it on the illicit market, five from home-grown sources, and two obtained their supply from an association of cannabis consumers. Of all the women from the cannabis group, 19 had informed their doctor of their consumption. Lastly, 19 (68%) of the women from the cannabis group reported having reduced pharmacological treatment with prescription medicines thanks to self-medication with cannabis. Patients who used cannabis as self-medication used it both to relieve pain and to reduce the other symptoms associated with fibromyalgia.

Cannabis and fibromyalgia

Both groups were administered a series of scales to evaluate the level of severity of the illness, called the ‘Fibromyalgia impact questionnaire’ (, The Pittsburgh Sleep Quality Index, (…pdf) and a questionnaire on quality of life called SF-36, ( In addition to this, the women in the cannabis group were asked to indicate, on a scale of one to five, their perceived relief from the consumption of cannabis for a series of symptoms: pain, sleep problems, muscle stiffness, mood disorders, anxiety, headaches, tiredness, morning tiredness and digestive problems. The patients reported relief in almost all the symptoms in proportions ranging from 81% for sleep disorders to 14% for headaches. Not one woman reported a worsening of symptoms secondary to consumption.

The women were also asked to rate from 0 to 100, two hours before and two hours after consuming cannabis, the relief felt in a series of symptoms: pain, stiffness, relaxation, tiredness, wellbeing. In all of these symptoms there was a significant improvement when the ratings from two hours after were compared with the ratings from two hours before consuming cannabis. Finally, of the three aforementioned scales given to all the patients, only in the ‘mental health’ subscale from the SF-36 were there differences between the groups, with higher points from the cannabis group, which implies that the subjective benefits referred to do not necessarily manifest themselves in a clinical improvement. Future investigations must therefore elucidate whether the benefit referred to by the patients with fibromyalgia who self-medicated with cannabis is relevant from a clinical point of view.

Cannabis vs Pharmacological treatments

A healthy brain compared to the brain of a patient suffering from Fybromalgia
A healthy brain compared to the brain of a patient suffering from Fybromalgia

In summary, this is a naturalistic study, which has intrinsic limitations in terms of extracting definitive conclusions, but at the same time high ecological validity in terms of accurately reflecting the day-to-day life of patients with this type of pathology. It is worth highlighting in any case that the patients from the cannabis group were refractory to habitual treatments and that they had turned to cannabis as a last resort.

It would be interesting to investigate whether, in women suffering from this condition who are less resistant to treatment, cannabis could be more useful than the pharmacological treatments used, which have more side effects. In any case, the fact that thanks to consuming cannabis, these women were able to reduce their intake of other medications, didn’t report suffering any major side effects from its consumption and subjectively perceived relief in the majority of the symptoms suffered, bearing in mind that the medication in current use shows little effectiveness in treating the symptoms, finding some type of relief at a negligible physiological cost could in itself represent huge progress in the treatment of their illness.

On another level as well, studies like this one will allow us to clarify in the future whether illnesses such as fibromyalgia are due to a deregulation of the endocannabinoid system and in this way gain an insight into the etiopathogenesis of this highly debilitating illness.

Author: Silent Jay @ Sensiseeds

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