Chronic Fatigue Syndrome

General Information

Chronic fatigue syndrome, or CFS, is a devastating and complex disorder characterized by overwhelming fatigue that is not improved by bed rest and that may be worsened by physical or mental activity. People with CFS most often function at a significantly lower level of activity than they were capable of before the onset of illness.

In addition to these key defining characteristics, patients report various nonspecific symptoms, including weakness, muscle pain, impaired memory and/or mental concentration, insomnia, and post-exertional fatigue lasting more than 24 hours. In some cases, CFS can persist for years.

The cause or causes of CFS have not been identified and no specific diagnostic tests are available. Moreover, since many illnesses have incapacitating fatigue as a symptom, care must be taken to exclude other known and often treatable conditions before a diagnosis of CFS is made.

Case Definition

As of today, the cause or causes of CFS have not been identified and no specific diagnostic tests are available. Therefore, in order to be diagnosed with chronic fatigue syndrome, a patient must satisfy two criteria:

  • Have severe chronic fatigue for at least 6 months or longer that is not relieved by rest and not due to medical or psychiatric conditions associated with fatigue as excluded by clinical diagnosis; and
  • Concurrently have four or more of the following symptoms:
    • self-reported impairment in short-term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities
    • sore throat that's frequent or recurring
    • tender cervical or axillary lymph nodes
    • muscle pain
    • multi-joint pain without swelling or redness
    • headaches of a new type, pattern, or severity
    • unrefreshing sleep and
    • post-exertional malaise (extreme, prolonged exhaustion and sickness following physical or mental activity) lasting more than 24 hours.

The fatigue and impaired memory or concentration must have impaired normal daily activities, along with other symptoms that must have persisted or recurred during 6 or more consecutive months of illness and must not have predated the fatigue.

Causes of CFS

The cause or causes of CFS remain unknown, despite a vigorous search. While a single cause for CFS may yet be identified, another possibility is that CFS represents a common endpoint of disease resulting from multiple sudden causes. Some of the possible causes of CFS might be due to infectious agents, immunological dysfunction, stress activating the hypothalamic-pituitary adrenal (HPA) axis, neurally mediated hypotension, and/or nutritional deficiency.

Symptoms of CFS

The primary symptoms of CFS are severe fatigue, weakening that is not improved by bed rest and may be worsened with physical or mental activity. It is an all-encompassing fatigue that results in dramatic decline in both activity level and stamina.

The fatigue of CFS is accompanied by characteristic symptoms lasting at least 6 months. These symptoms include:

  • self-reported impairment in short-term memory or concentration severe enough to cause substantial reduction in previous levels of occupational, educational, social, or personal activities
  • sore throat that's frequent or recurring
  • tender cervical (neck) or axillary (armpit) lymph nodes
  • muscle pain
  • multi-joint pain without swelling or redness
  • headaches of a new type, pattern, or severity
  • unrefreshing sleep and
  • post-exertional malaise (extreme, prolonged exhaustion and sickness following physical or mental activity) lasting more than 24 hours.

The symptoms listed above are the symptoms used to diagnose this illness. However, many CFS patients may experience other symptoms, including irritable bowel, depression or psychological problems, chills and night sweats, visual disturbances, allergies or sensitivities to foods, odors, chemicals, medications, or noise, brain fog, difficulty maintaining upright position, dizziness, balance problems or fainting.

Diagnosis of CFS

Because there is no blood test, brain scan or other lab test to diagnose CFS, it is a diagnosis of exclusion. A health care professional will first take a detailed patient history, then a thorough physical and mental status examination. Next, a series of laboratory screening tests will be ordered to help identify or rule out other possible causes of symptoms. There may also be additional tests to follow up on results of the initial screening tests. A diagnosis of insufficient fatigue could be made if a patient has been fatigued for 6 months or more, but does not meet the symptom criteria for CFS.

Treatment of CFS

Managing chronic fatigue syndrome can be as complex as the illness itself. There is no cure yet, no prescription drugs have been developed specifically for CFS, and symptoms vary considerably over time. These factors complicate the treatment picture, which require patients and doctors to always monitor and change treatment strategies.

One key to managing CFS is each patient needs to work with a team of doctors and other health care practitioners, which might include mental health professionals, rehabilitation specialist, and physical or exercise therapists, to create an individualized treatment program. This program should be based on a combination of therapies that address coping techniques, symptoms and activity management.

Centers for Disease Control and Prevention
Last updated: October 15, 2010

Page last modified or reviewed by athealth.com on February 1, 2014