Fibromyalgia is difficult to diagnose because many of the symptoms mimic those of other diseases. The physician reviews the patient's medical history and makes a diagnosis of fibromyalgia based on a history of chronic widespread pain that persists for more than 3 months. The American College of Rheumatology (ACR) has developed criteria for fibromyalgia that physicians can use in diagnosing the disease. According to ACR criteria, a person is considered to have fibromyalgia if he or she has widespread pain in combination with tenderness in at least 11 of 18 specific tender point sites. Treatment of fibromyalgia requires a comprehensive approach. The physician, physical therapist, and patient may all play an active role in the management of fibromyalgia. Studies have shown that aerobic exercise, such as swimming and walking, improves muscle fitness and reduces muscle pain and tenderness. Heat and massage may also give short-term relief. Antidepressant medications may help elevate mood, improve quality of sleep, and relax muscles. Fibromyalgia patients may benefit from a combination of exercise, medication, physical therapy, and relaxation.