The Effects of THC-Rich Cannabis Oil on Symptoms and Quality of Life in Fibromyalgia Patients

The Effects of THC-Rich Cannabis Oil on Symptoms and Quality of Life in Fibromyalgia Patients

Fibromyalgia is one of the most common chronic pain conditions, affecting up to 5% of people in the UK, according to the NHS. The condition can affect people of any age; however, it is most commonly diagnosed in patients aged between 30 and 50. It is also believed that Fibromyalgia affects around 7 times as many women as men.

The cause of Fibromyalgia remains unclear, though it is believed to be linked to certain chemicals in the brain and changes in how the central nervous system (CNS) processes pain messages. Some evidence suggests that inherited genes can also play a part in the development of the condition. Fibromyalgia is often found to be triggered by a physically or emotionally stressful event, such as injury, infection, or operation, giving birth, the death of a loved one, or the breakdown of a relationship.

As it is unclear exactly what causes the condition, treatment can be difficult. Therefore, treatment options focus on symptom relief and improving the quality of life of those living with the condition. Existing treatment options include antidepressants and more traditional pain relief as well as talking therapies (such as cognitive behavioural therapy or counselling), and lifestyle change. However, some clinical trials and studies have aimed to understand how cannabinoids could potentially improve symptoms and quality of life in fibromyalgia patients.

Cannabis as a Treatment for Pain Conditions

While recent decades, characterised by prohibition policies, have seen a decline in the medical use of cannabis, the plant has been used for centuries as a treatment for pain conditions. Furthermore, as more countries continue to liberalise access to medical cannabis, a number of studies have demonstrated that cannabinoids (compounds produced by the cannabis plant) can be effective in the treatment of some pain conditions.

One such study, published recently in the journal Pain Medicine, aimed to determine the benefit of THC-rich cannabis oil on symptoms and quality of life (QoL) of fibromyalgia patients.

How were the effects of cannabis assessed?

The randomised, double-blind, placebo-controlled clinical trial compared the effects of cannabis oil with those of a placebo in seventeen patients from a community health centre in Florianopolis, Brazil, in 2019. Eight of the participants were assigned to the cannabis group and nine to the placebo group. Each participant, from both groups, were given identical 30ml bottles containing either placebo or a 24.44mg/ml THC -0.51mg/ml CBD cannabis oil preparation.

Each participant was prescribed one drop – which in the cannabis group equated to 1.2mg THC and 0.02mg CBD – each day. All participants were assessed at baseline and then every ten days for eight weeks. Patients were asked to fill out the Fibromyalgia Impact Questionnaire (FIQ) at each visit. The FIQ is a self-report test “that evaluates physical function, work status, well-being, and associated physical and mental symptoms in Fibromyalgia patients.

The Results

No significant differences in FIQ scores were identified between the two groups at baseline (prior to treatment). However, it was noted at this stage that the cannabis group recorded greater scores in the “physical impairment” category – meaning they suffered greater impairment.

After eight weeks of treatment, however, the cannabis group presented improvements in several areas, with a lower overall score on the FIQ when compared to the placebo group. With a mean dose of 3.6 drops (4.4mg THC and 0.08mg CBD) by the final visit, participants in the cannabis group recorded improved FIQ scores in the “feel good”, “do work”, and “pain” categories.

Overall, the cannabis group recorded a statistically significant reduction in FIQ score, going from 75.5 points pre-intervention to 30.5 points post-intervention. In addition, 37.5% (3) patients in the cannabis group reported “better disposition for functional activities such as cooking and housekeeping. Another patient reported feeling more comfortable performing career activities.


The researchers conclude that the cannabis preparation used in this trial demonstrated significant and promising reductions in numerous symptoms commonly associated with Fibromyalgia. They were particularly motivated by the improvement in the “feel good” item in patients’ FIQs as it went from having the highest score in both groups pre-intervention to the lowest score in the cannabis group post-intervention.

It is believed that this study was the first to demonstrate the benefit of THC-rich whole plant extract on symptoms and quality of life of patients living with Fibromyalgia. The researchers determine from these results that cannabis could be a low-cost and well-tolerated therapy for the relief of the condition.