What's in a Name: Fibro vs. CFS Fibromyalgia and chronic fatigue syndrome (CFS) share a number of symptoms, and the names are often used interchangeably in the medical literature. If you're confused about the difference between the syndromes, you're not alone. Even doctors are confused. Many experts, however, think fibromyalgia and CFS are the same -- or are at least variations of the same -- pain and fatigue syndrome. Research shows that between 50 percent and 70 percent of people with fibromyalgia also fit the criteria for CFS, and vice versa. Because the symptoms are so similar, the difference between one diagnosis and another may be simply a matter of degree. "Most patients with CFS have some kind of pain, and, of course, that is a hallmark of fibromyalgia. And most patients with fibromyalgia report fatigue -- a hallmark of CFS. Likewise, both involve a high frequency of sleep and cognitive disturbances," says Cary Engleberg, MD, chief of the infectious diseases division at the University of Michigan Medical School in Ann Arbor. The diagnosis also may depend on whether your doctor is more familiar with the criteria for CFS, developed by the Centers for Disease Control and Prevention (CDC) or those for fibromyalgia, developed by the American College of Rheumatology. There are a few documented differences between the conditions. Fibromyalgia often is traced to an injury or physical or emotional trauma, whereas CFS tends to have a flu-like onset. Researchers have found that people with fibromyalgia may have abnormal levels of several chemicals, such as substance P and serotonin, used by the body to transmit and respond to pain signals. Also, people with CFS only do not have tender points. These findings have led to different trends in research. Many fibromyalgia researchers have explored problems with pain transmission and pain amplification that may affect the condition. Researchers who study CFS have tended instead to investigate what role viruses may play in triggering CFS. Until researchers determine conclusively the fundamental biological, neurological and psychological differences between the syndromes, the diagnostic label makes little difference as long as both the physician and the patient take a comprehensive approach to treating symptoms. "Rational treatment consists of maintaining good general health -- in other words, a balanced diet and exercise as tolerated, and symptomatic relief of pain, sleep or mood disorders with carefully selected medications or cognitive behavioral therapy," says Dr. Elgleberg.