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Health A-Z

Medical Content Created by the Faculty of the
Harvard Medical School

Fibromyalgia

What Is It?

People with fibromyalgia have widespread pain, aches and stiffness in muscles and joints throughout the body along with unusual tiredness. There is no known cause of fibromyalgia. In addition, doctors can't find a physical reason for the symptoms. Blood tests, X-rays and other tests usually are normal in people with fibromyalgia.

Fibromyalgia is a controversial illness. Some physicians don't believe that it's a medical illness but may be a reflection of psychological distress or stress. However, there's no proof of a psychological cause either. Until we have a better understanding of the disorder, it's likely to remain controversial.

It may be that fibromyalgia has more than one cause. Some researchers have suggested that it's related to abnormalities in a non-dream part of the sleep cycle or to low levels of serotonin, a brain chemical that regulates sleep and pain perception. Other theories have linked fibromyalgia to low levels of somatomedin C, a chemical related to muscle strength and muscle repair, or to high levels of substance P, a chemical that affects the threshold at which a person experiences pain. Still others have cited trauma, blood-flow abnormalities in the muscles, viral infections or other infections as possible triggers of fibromyalgia.

Fibromyalgia affects an estimated 3.4% of women and 0.5% of men in the United States, or 3 million to 6 million Americans. It most commonly affects women of childbearing age or older. In fact, some estimates suggest that more than 7% of women in their 70s have fibromyalgia. Many people with fibromyalgia also have psychiatric problems such as depression, anxiety or eating disorders, although the relationship between them remains unclear.

From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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