Fibromyalgia's main symptom is chronic pain, an all-over ache. Because the pain is incessant and does not respond well to medication, it can be extremely lifestyle-threatening even though the disease is neither fatal nor degenerative. (It's also not contagious.) Fibromyalgia may also include:

Fibromyalgia has no known cause, only unproven theories. Certain factors such as stress, poor sleep, or physical or emotional trauma may trigger the condition.

Fibromyalgia is difficult to diagnose, more so because some physicians refuse to believe in its existence. Typically, doctors diagnose fibromyalgia only after they have eliminated other conditions.

The American College of Rheumatology has established some diagnostic guidelines for fibromyalgia. They include "having widespread aching for at least 3 months and a minimum of 11 locations on your body that are abnormally tender under relatively mild pressure." These areas are called tender points. Some of them are mapped here:

Before the American College of Rheumatology endorsed the term in 1990, the condition was referred to by names such as fibrositis, chronic muscle pain syndrome, psychogenic rheumatism and tension myalgias.

It is linked to chronic fatigue syndrome.