A complex, multifactorial disease affecting the musculoskeletal system mainly in adult women (90%) (40-60 years) and characterized by widespread chronic muscle pain associated with profound fatigue, stiffness, insomnia, memory and mood changes. It may appear gradually and worsen over time, or it may appear after a triggering event such as physical and/or psychological trauma or infection.

The exact causes of fibromyalgia are unknown. Experts believe that it is a set of factors that lead to the onset of its symptoms, including genetic, infectious, hormonal factors, physical and psychological trauma.

Chronic Fatigue Syndrome (CFS) often overlaps with fibromyalgia. It is a disease of unknown etiology, characterized by unexplained and debilitating chronic fatigue, a real deep exhaustion, which lasts for several months and which occurs even after minor efforts and gives chronic and recurrent fever, pain in the laterocervical and axillary lymph glands, diffuse muscle and joint pain, pharyngitis and neuro-psychological symptoms such as sleep disorders, difficulty concentrating, memory loss and reactive depression.

It has been estimated that 20-70% of patients with fibromyalgia also meet the criteria for CFS and, conversely, 35-70% of patients with CFS also have co-occurring fibromyalgia.