Chronic Fatigue Syndrome


What Is It?

Chronic fatigue syndrome (CFS) is a controversial and complicated illness that is characterized by at least six months of fatigue (feeling extremely tired or exhausted) that cannot be explained. In many patients with CFS, the disorder begins suddenly, often following a flulike infection or an episode of physical or psychologic trauma, such as surgery, a traumatic accident or the death of a loved one. In other cases, CFS develops gradually.

Currently, the exact cause of chronic fatigue syndrome remains a mystery. Although the illness sometimes occurs after an infection with B. burgdorferi (Lyme disease bacteria) or an episode of infectious mononucleosis, there is no proof that these infections cause CFS. Researchers also have been unable to link CFS to immune-system problems or allergies. So far, the most promising theory describes CFS as a multi-system disorder that disturbs the complex relationship between the hypothalamus (a part of the brain that regulates hormones and vital functions) and the pituitary and adrenal glands. This theory is supported by studies that link CFS to a form of a condition called neurally mediated hypotension, which is abnormally low blood pressure caused by a problem in the nervous system. The most recent studies, however, have found no consistent connection between low blood pressure and chronic fatigue, so the role of brain function and blood-pressure regulation to the condition remains uncertain.

In the United States, federal health authorities estimate that CFS currently affects four to 10 of every 100,000 Americans older than age 18, and women are afflicted twice as often as men. Although the illness is most common in people 25 to 45 years old, CFS can attack people of all age groups, including children.

Most cases of CFS affect isolated individuals. However, at least 30 outbreaks of CFS also have been reported, during which many people in the same area suddenly developed the illness at the same time. Again, despite the larger numbers of patients involved in these outbreaks, health experts have failed to identify a cause for their CFS symptoms.


The most prominent symptom of chronic fatigue syndrome is an unexplained feeling of fatigue, which is not relieved by rest. This fatigue must be severe enough to decrease the activity level at home, work or school. Many physicians look for the fatigue to be severe enough to reduce someone’s activity level by 50 percent or more. In addition, to be diagnosed with CFS, patients should have at least four of the following symptoms for at least six months:

  • Impaired concentration or short-term memory — severe enough to affect routine activities at home, work, school or social functions
  • Sore throat
  • Enlarged lymph nodes (swollen glands) in the neck or underarm area
  • Muscle pain
  • Pain in several joints, with no redness or swelling
  • Headaches that are different in some way — a new type of headache pain, a new pattern of headaches, or headaches that are more severe than before
  • Sleep that doesn’t refresh — not feeling rested upon waking
  • An extreme reaction to exertion — sick for 24 hours or more after exercise or strenuous activity

Although people with CFS can have other feeling symptoms, they are not part of the official definition of CFS. For example, 60 percent to 80 percent of people with CFS have symptoms of some type of mental illness, especially depression. However, some investigators of chronic fatigue syndrome use the term CFS only for those people who do not have symptoms of depression, anxiety or related disorders. Other people with CFS have symptoms of severe allergies, allergic rhinitis (hay fever) or sinusitis.


Your doctor will ask about your symptoms of persistent, severe fatigue, together with other symptoms of CFS.

There is no laboratory test or procedure to confirm the diagnosis of CFS. Until a better way is found, doctors must diagnose CFS by eliminating other illnesses as the cause of symptoms. Once other illnesses are excluded, the best possible explanation is CFS.

For this reason, your doctor will ask about symptoms of other illnesses that can be confused with chronic fatigue syndrome, including:

  • Hypothyroidism
  • Adrenal insufficiency
  • Cardiac disorders
  • Sleep apnea or narcolepsy
  • Side effects of medications
  • Cancer
  • Hepatitis B or C
  • Certain psychiatric illnesses, especially major depression; bipolar affective disorder; schizophrenia or delusional disorders; dementia
  • The eating disorders anorexia nervosa and bulimia
  • Drug abuse, including alcohol abuse
  • Severe obesity

As part of this process of exclusion, your doctor will perform a physical examination and assess your mental status. Some basic urine and blood tests will be ordered. In addition, your doctor will order thyroid tests and blood tests to measure liver enzymes to evaluate liver function and/or liver damage. Additional, more specialized testing may be needed, including tilt-table testing to look into whether neurally mediated hypotension exists. In this test, the patient is placed on a table that tilts to evaluate how blood pressure, heart rate and other measurements respond to the stress of standing up.

Expected Duration

By definition, symptoms of CFS must persist for at least six months. In many people, symptoms persist for several years, but they tend to be worst in the first one to two years.


Since the cause of CFS remains unknown, there is no way to prevent it.


There is no specific treatment for CFS. However, CFS patients in research studies have had positive effects from exercise programs and cognitive behavioral therapy, which is counseling designed to change behavior and beliefs about the condition. No one approach is best for everyone with CFS, and cure is rarely achieved.

In general, doctors use a combination of the following:

  • Lifestyle changes — Patients are encouraged to slow down and to avoid physical and psychological stress. They learn to save their energy for essential activities at home or work and to cut back on less important activities.
  • Resuming exercise gradually but steadily — With the help of a physical therapist, patients begin an exercise program in which physical activity is increased gradually.
  • Treating existing psychiatric problems — Psychiatric problems can be treated with medication, cognitive behavioral therapy or a combination of the two. For patients with depression, several antidepressant medications are available.
  • Treating existing pain — Aspirin, acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (NSAIDs) are used to treat headaches, muscle pain and joint pain. Antidepressant medications also may help to reduce chronic pain.
  • Treating existing allergy symptoms — Antihistamines and decongestants are used to treat allergy symptoms.
  • Experimental therapies — Researchers who believe that CFS is caused by neural hypotension have reported some success in treating CFS with fludrocortisone (Florinef), beta-adrenergic blocking agents and other medications. However, these are not always effective.

When To Call A Professional

Call your doctor if you have symptoms of CFS, especially if extreme fatigue prevents you from fully participating in activities at home, work or school.


People with CFS usually experience their most severe symptoms in the first one to two years of illness. After that time, a small number of people recover totally, and a small number become totally incapacitated. For most people, there is gradual improvement, although they usually do not achieve the level of activity they were capable of before getting the disease. Recovery tends to be less likely among people who:

  • Have symptoms for a longer time
  • Have longstanding depression
  • Are old than 40 when symptoms start
  • Have multiple physical symptoms
  • Believe that an undiagnosed medical illness is causing the fatigue

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.