Fibromyalgia is a chronic condition causing pain, stiffness, and tenderness of the muscles, tendons, and joints. Fibromyalgia is also characterized by restless sleep, awakening feeling tired, fatigue, anxiety, depression, and disturbances in bowel function. Fibromyalgia was formerly known as fibrositis.
While fibromyalgia is one of the most common diseases affecting the muscles, its cause is currently unknown. The painful tissues involved are not accompanied by tissue inflammation. Therefore, despite potentially disabling body pain, patients with fibromyalgia do not develop body damage or deformity. Fibromyalgia also does not cause damage to internal body organs. In this sense, fibromyalgia is different from many other rheumatic conditions (such as rheumatoid arthritis, systemic lupus, and polymyositis). In those diseases, tissue inflammation is the major cause of pain, stiffness, and tenderness of the joints, tendons and muscles, and it can lead to joint deformity and damage to the internal organs or muscles.