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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Jerry R. Balentine, DO, FACEP

Jerry R. Balentine, DO, FACEP

Dr. Balentine received his undergraduate degree from McDaniel College in Westminster, Maryland. He attended medical school at the Philadelphia College of Osteopathic Medicine graduating in1983. He completed his internship at St. Joseph's Hospital in Philadelphia and his Emergency Medicine residency at Lincoln Medical and Mental Health Center in the Bronx, where he served as chief resident.

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In this Article

• Chronic fatigue syndrome (CFS) facts
• What is chronic fatigue syndrome?
• What causes chronic fatigue syndrome?
• What are risk factors for chronic fatigue syndrome?
• What are symptoms and signs of chronic fatigue syndrome?
• What are chronic fatigue syndrome symptoms in men?
• What are chronic fatigue syndrome symptoms in women?
• How is chronic fatigue syndrome diagnosed?
• What is the treatment for chronic fatigue syndrome?
• Is there a cure for chronic fatigue syndrome?
• What is the prognosis of chronic fatigue syndrome?
• Can chronic fatigue syndrome be prevented?
• Where can people find additional information about chronic fatigue syndrome?
• Chronic Fatigue FAQs
• Patient Comments: Chronic Fatigue Syndrome - Coping
• Patient Comments: Chronic Fatigue Syndrome - Symptoms
• Patient Comments: Chronic Fatigue Syndrome - Treatment
• Find a local Rheumatologist in your town
• Chronic Fatigue Syndrome Index

Controversy about the definition of chronic fatigue syndrome (CFS) finally led an international panel of CFS research experts in 1994 to establish a precise definition of CFS so that the syndrome could actually be diagnosed. There are two criteria developed by this panel that both define and diagnose CFS. The patient must have both of the following criteria:

1. Have severe chronic fatigue of 6 months or longer duration with other known medical conditions excluded by clinical diagnosis
2. Concurrently have four or more of the following symptoms: substantial impairment in short-term memory or concentration; sore throat; tender lymph nodes in neck or armpits; unexplained muscle pain; multi-joint pain without swelling or redness; headaches of a new type, pattern, or severity; non-refreshing sleep; and post-exertion malaise lasting more than 24 hours

In addition, four symptoms of the symptoms listed above must have persisted or recurred during 6 or more consecutive months of illness and must not have predated the severe chronic fatigue (the symptoms must have occurred at the same time or after severe chronic fatigue appeared, but not before). Although most of the medical community accepts this definition, there are some that either do not accept this definition or think the criteria needs revision.

Why so much controversy? There are at least three major reasons for controversy:

1. Chronic fatigue is a symptom of many illnesses, so chronic fatigue syndrome had to have criteria that distinguished it from similar medical conditions that have chronic fatigue as a major symptom (for example, fibromyalgia, chronic mononucleosis, myalgic encephalomyelitis, neurologic problems, sensitivity to certain chemicals). Other treatable illnesses and conditions that may have chronic fatigue as one symptom among many others include hypothyroidism, cancers, autoimmune diseases, adrenal gland problems, subacute or chronic infections, obesity, sleep apnea, narcolepsy, reactions to medicines, hormonal disorders, schizophrenia, bipolar disorders, eating disorders, depression, alcohol and substance abuse, and malingering.
2. In addition to the two criteria above needed to fit both the definition and diagnosis of CFS, many patients have additional symptoms that, depending on their severity, may predominate and overshadow the CFS symptom criteria. These symptoms include chest pain, abdominal pain, shortness of breath, chronic cough, diarrhea, nausea, night sweats, jaw and muscle stiffness and pain, double vision, and psychological problems such as panic attacks, anxiety, and depression.
3. There is no laboratory test that can give a definitive diagnosis of CFS, and there are no physical signs that specifically identify CFS.

Consequently, the disease is diagnosed by excluding the diseases that may cause the symptoms (termed a diagnosis of exclusion) listed above yet still fit the two defined criteria established by the panel of CFS experts in 1994. It is not unusual for patients to undergo an extensive battery of tests to rule out other diseases before a patient is determined to fit the CFS diagnostic criteria. Unfortunately, many patients that have subsequently been diagnosed to have CFS also have had some of the conditions and symptoms listed above. Without the CFS criteria, diagnosis would even be more controversial.

Controversy still remains. Some individuals want to rename the disease. Some clinicians want to change the 1994 criteria and others do not. Until a definitive cause is proven, controversies about names, diagnosis, treatments, and other aspects of CFS will likely remain.