chronic syndrome that is characterized by musculoskeletal pain, often at multiple anatomical sites, that occurs in the absence of an identifiable physical or physiological cause. A significant number of persons with fibromyalgia also have mental disorders, especially depression. Fibromyalgia is most commonly diagnosed in young and middle-aged women.

Many persons with fibromyalgia also have overlapping symptoms of other so-called functional somatic syndromes—especially chronic fatigue syndrome—such as fatigue, stiffness, irritable bowel syndrome, and disturbed or unrefreshing sleep. However, without a diagnostic test it is impossible to verify or disprove the similarity of fibromyalgia to the other functional somatic syndromes or, for that matter, to establish its existence as a distinct disorder. The problem is complicated further by the fact that virtually all of the symptoms experienced by persons with fibromyalgia are common, nonspecific, and variable.

A hallmark of fibromyalgia (and the other functional somatic syndromes) is the tenacity with which sufferers insist their problems are of physical rather than psychogenic origin—even though many have been diagnosed with a mental disorder—and the belief that physicians do not take their complaints seriously. However, it seems clear that few, if any, fibromyalgia patients are malingering.

The underlying cause of fibromyalgia is completely unknown, although most researchers view the disorder as an aberrant and nonspecific response to various stressors such as trauma or infection. It seems likely that fibromyalgia is of psychogenic origin.

No treatment for fibromyalgia has been proved fully effective. Medications, physical therapy, or counseling may be employed to reduce disability and to help the patient cope with the chronic illness. Although symptoms sometimes improve, full recovery over a short time frame appears to be the exception.