Chronic Fatigue Syndrome Chronic Fatigue Syndrome
Center for Disease Control and Prevention

Chronic fatigue syndrome shares symptoms with many other disorders. Fatigue, for instance, is found in hundreds of illnesses, and 10% to 25% of all patients who visit general practitioners complain of prolonged fatigue. The nature of the symptoms, however, can help clinicians differentiate CFS from other illnesses.

As the name chronic fatigue syndrome suggests, this illness is accompanied by fatigue. However, it’s not the kind of fatigue patients experience after a particularly busy day or week, after a sleepless night or after a stressful event. It’s a severe, incapacitating fatigue that isn’t improved by bed rest and that may be exacerbated by physical or mental activity. It’s an all-encompassing fatigue that results in a dramatic decline in both activity level and stamina.

People with CFS function at a significantly lower level of activity than they were capable of prior to becoming ill. The illness results in a substantial reduction in occupational, personal, social or educational activities.

A CFS diagnosis should be considered in patients who present with six months or more of unexplained fatigue accompanied by other characteristic symptoms. These symptoms include:

cognitive dysfunction, including impaired memory or concentration
postexertional malaise lasting more than 24 hours (exhaustion and increased symptoms) following physical or mental exercise
unrefreshing sleep
joint pain (without redness or swelling)
persistent muscle pain
headaches of a new type or severity
tender cervical or axillary lymph nodes
sore throat
Other Common Symptoms

In addition to the eight primary defining symptoms of CFS, a number of other symptoms have been reported by some CFS patients. The frequency of occurrence of these symptoms varies among patients. These symptoms include:

irritable bowel, abdominal pain, nausea, diarrhea or bloating
chills and night sweats
brain fog
chest pain
shortness of breath
chronic cough
visual disturbances (blurring, sensitivity to light, eye pain or dry eyes)
allergies or sensitivities to foods, alcohol, odors, chemicals, medications or noise
difficulty maintaining upright position (orthostatic instability, irregular heartbeat, dizziness, balance problems or fainting)
psychological problems (depression, irritability, mood swings, anxiety, panic attacks)
jaw pain
weight loss or gain
Clinicians will need to consider whether such symptoms relate to a comorbid or an exclusionary condition; they should not be considered as part of CFS other than they can contribute to impaired functioning.

Clinical Course

The severity of CFS varies from patient to patient, with some people able to maintain fairly active lives. By definiton, however, CFS significantly limits work, school and family activities.

While symptoms vary from person to person in number, type and severity, all CFS patients are functionally impaired to some degree. CDC studies show that CFS can be as disabling as multiple sclerosis, lupus, rheumatoid arthritis, heart disease, end-stage renal disease, chronic obstructive pulmonary disease (COPD) and similar chronic conditions.

CFS often follows a cyclical course, alternating between periods of illness and relative well-being. Some patients experience partial or complete remission of symptoms during the course of the illness, but symptoms often reoccur. This pattern of remission and relapse makes CFS especially hard for patients and their health care professionals to manage. Patients who are in remission may be tempted to overdo activities when they’re feeling better, which can exacerbate symptoms and fatigue and cause a relapse. In fact, postexertional malaise is a hallmark of the illness.

The percentage of CFS patients who recover is unknown, but there is some evidence to indicate that the sooner symptom management begins, the better the chance of a positive therapeutic outcome. This means early detection and treatment are of utmost importance. CDC research indicates that delays in diagnosis and treatment may complicate and prolong the clinical course of the illness.

Diagnostic Resources

Several resources have been created to assist health care professionals in diagnosing and managing CFS. These resources can be accessed below:

CFS Toolkit: Fact Sheets for Health Care Professionals
Provider Resource Guide
PDF (2 Pages / 136 KB)