Institute of Medicine Diagnostic Criteria for Chronic Fatigue Syndrome
Diagnosis requires that the patient have the following three symptoms:
1A substantial reduction or impairment in the ability to engage in preillness levels of occupational, educational, social, or personal activities, which persists for more than 6 mo and is accompanied by fatigue, which is often profound, is of new or definite onset (not lifelong), is not the result of ongoing excessive exertion, and is not substantially alleviated by rest;
2Postexertional malaise*; and
3Unrefreshing sleep*
At least one of the two following manifestations is also required:
1Cognitive impairment* or
2Orthostatic intolerance
  • * Frequency and severity of symptoms should be assessed. The diagnosis should be questioned if patients do not have these symptoms at least half of the time with moderate, substantial, or severe intensity.