Fibromyalgia is a common condition characterized by widespread pain in joints, muscles, tendons, and other soft tissues. Some other problems commonly linked with fibromyalgia include fatigue, morning stiffness, sleep problems, headaches, numbness in hands and feet, depression, and anxiety. Fibromyalgia can develop on its own, or secondary to other musculoskeletal conditions, such as rheumatoid arthritis, or systemic lupus.

Diagnosis of fibromyalgia requires a history of a least three months of widespread pain, and pain and tenderness in at least 11 of 18 tender-point sites. These tender-point sites include fibrous tissue or muscles of the:

• Neck
• Shoulders
• Chest
• Rib cage
• Lower back
• Thighs
• Knees
• Arms (elbows)
• Buttocks

The overwhelming characteristic of fibromyalgia is long-standing, body-wide pain with defined tender points. Tender points are distinct from trigger points seen in other pain syndromes. (Unlike tender points, trigger points can occur in isolation and represent a source of radiating pain, even in the absence of direct pressure.)

Fibromyalgia pain can mimic the pain experienced by people with various types of arthritis. With fibromyalgia syndrome alone, the significant joint swelling, destruction, and deformity seen in patients with diseases, such as rheumatoid arthritis does not occur.

The soft-tissue pain of fibromyalgia is described as deep-aching, radiating, gnawing, shooting or burning, and ranges from mild to severe. Fibromyalgia sufferers tend to waken with body aches and stiffness.

For some patients, pain improves during the day and increases again during the evening, though many patients with fibromyalgia have day-long, unrelenting pain. Pain can increase with activity; cold, damp weather; anxiety; and stress.

The cause of this disorder is unknown. Physical or emotional trauma may play a role in development of the syndrome. A number of lines of evidence suggest that fibromyalgia patients have abnormal pain transmission responses.

It has been suggested that sleep disturbances, which are common in fibromyalgia patients, may actually cause the condition. Another hypothesis suggests that the disorder may be associated with changes in skeletal muscle metabolism, possibly caused by decreased blood flow, which could cause chronic fatigue and weakness.

Others have suggested that an infectious microbe, such as a virus, triggers the illness. At this point, no such virus or microbe has been identified.

Pilot studies have shown a possible inherited tendency toward the disease, though evidence is very preliminary.

The disorder has an increased frequency among women 20 to 50 years old. The prevalence of the disease has been estimated between 0.7% and 13% for women, and between 0.2% and 3.9% for men.