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Unknown: Chronic Fatigue Syndrome

Unknown: Chronic Fatigue Syndrome

Causes and Symptoms
The Future
For more information


Chronic fatigue syndrome, or CFS, is a disorder of unknown origin that is characterized by unexplained tiredness lasting a year or more and is accompanied by cognitive (thought-related) difficulties as well as headaches, pain in the muscles and joints, and other symptoms.


CFS is a disorder that affects a number of body systems, ranging from digestive problems, soreness in joints and muscles, and difficulties with thinking and memory to sleeping problems, chest pain, headaches, and extreme tiredness that is not relieved by rest. Although the disorder bears some resemblance to such other disorders as Lyme disease or fibromyalgia, it includes some symptoms that do not occur in these disorders. The symptoms of CFS vary in severity from patient to patient and may vary over time for an individual patient.

Many cases of CFS start in the winter following an episode of influenza, an influenza-like illness, bronchitis, or other viral-like illness; however, a significant number appear to be triggered by a period of psychological stress. In a few cases, patients reported that their chronic fatigue began after a blood transfusion. Others have said that their symptoms began for no apparent reason.

CFS carries a high cost in time lost from work and social activities for many people. About half of patients diagnosed with CFS either have to reduce their work load or stop working altogether. One set of studies reported that only 42 percent of CFS patients were employed; of those working, 64 percent limited their work because of CFS, and only 19 percent of patients worked full time without limitations. The illness has a high psychological cost as well, since it makes it hard for people to carry out household chores, complete their education, or plan for the future. Many patients also worry about the long-term impact of chronic fatigue syndrome on their marriage or family relationships.


The Centers for Disease Control and Prevention (CDC) estimates that chronic fatigue syndrome affects between 1 and 4 million people in the United States. Most are young or middle-aged adults, with women being affected four times more frequently than men. It is not known for certain, however, whether women are more likely than men to get CFS or whether they are simply more likely to consult a doctor about their symptoms. Exact statistics about the frequency of CFS are difficult to compile because the definitions of the disorder have changed somewhat since the early 1990s.

CFS affects people of all races and ethnic groups. It appears to be as common among African Americans and Hispanics in the United States

as among Caucasians. It also appears to be equally common at all levels of education and income.

Causes and Symptoms

The cause or causes of CFS are still being debated. There are five major theories that researchers have proposed about possible causes of the disorder:

  • Viruses. At one time it was thought that CFS is caused by Epstein-Barr virus (EBV) or by the viruses that cause upper respiratory tract. It is now believed that there is no single virus that causes chronic fatigue syndrome.
  • An immune system disorder. This explanation is now thought unlikely because CFS does not cause tissue damage like lupus or rheumatoid arthritis.
  • A central nervous system disorder caused by high levels of emotional stress. Researchers are still looking into some aspects of this theory.
  • Nutritional deficiencies. Although some patients do develop food allergies or become intolerant of certain foods, there is no evidence that poor nutrition plays a role in causing CFS.
  • Chronic low blood pressure. The CDC is currently researching the effects of drugs to regulate low blood pressure in patients with CFS; some of these patients appear to benefit from these medications.

The CDC lists the following eight symptoms of chronic fatigue syndrome as primary symptoms (essential to diagnosing the disorder), all of which tend to come and go:

  • Significant problems with short-term memory or being able to concentrate
  • Sore throat
  • Soreness in the lymph nodes
  • Muscle pain
  • Pain in several different joints that is not accompanied by redness or swelling
  • Headaches
  • The patient is not refreshed after sleep
  • Fatigue that lasts longer than 24 hours after any kind of exertion

Other symptoms that are not considered primary symptoms but are reported by about 50 percent of people with chronic fatigue syndrome include:

  • Earaches, jaw pain, chronic coughing
  • Chills and night sweats
  • Nausea, vomiting, abdominal cramps
  • Dizziness and problems with balance
  • Depression, anxiety, and panic attacks
  • Shortness of breath
  • Dry eyes and vision problems
  • Chest pain
  • Diarrhea
  • Weight loss or gain
  • Allergies or increased sensitivity to light, noise, odors, chemicals, or medications


There are no laboratory tests or imaging studies that can be used to diagnose chronic fatigue syndrome. The diagnosis is primarily a diagnosis of exclusion, which means that the doctor begins by ruling out some diseases and disorders that have similar symptoms. These include disorders that cause fatigue, such as sleep apnea or a thyroid disorder; medications that may cause unusual tiredness; alcohol abuse; recurrence of cancer; severe obesity; or a previous diagnosis of depression, schizophrenia, or an eating disorder.

The CDC has defined two major criteria for CFS. The first criterion is that the person must have severe fatigue for a period of at least six months with other possible causes ruled out. The second criterion is having four or more of the primary symptoms listed above.


Treatment of chronic fatigue syndrome is usually multifaceted, consisting of recommendations about regular exercise and the importance of a nourishing diet, together with regular sleeping habits. About 70 percent of patients with CFS reported that they felt better after completing an exercise program that was designed to keep them active without making their fatigue worse. Antidepressant medications may be given to treat the depression, along with medications to treat the patient's allergies. Patients can also take non-aspirin pain relievers like acetaminophen or ibuprofen to relieve headaches or pain in the muscles and joints. There is, however, no single treatment for chronic fatigue syndrome that helps all patients who try it. What works best for most people is drawing up a personalized treatment plan together with their doctor.

Psychotherapy is recommended to help CFS patients cope more effectively with stress and to improve their chances of returning to full-time work. The type of psychotherapy that has been found to be most

useful for patients with chronic fatigue syndrome is cognitive behavioral therapy or CBT. In this form of therapy, patients learn to identify negative thoughts and behaviors that can complicate getting better, and to replace them with positive attitudes. In addition to CBT, support groups are helpful to many patients in learning to cope with the symptoms of the disease and its impact on their lives.

Some alternative and complementary therapies have been found to be effective in relieving the symptoms of chronic fatigue syndrome. These include gentle forms of physical exercise like yoga and t'ai chi as well as meditation, relaxation techniques, deep breathing exercises, and acupuncture.


The prognosis for full recovery from chronic fatigue syndrome is not good for the majority of patients. According to the CDC, between 8 percent and 63 percent of patients report some improvement in their symptoms after treatment. The best estimate, however, is that only 5–10 percent of patients make a full recovery.


There is no known way to prevent chronic fatigue syndrome because its causes are not yet fully understood.

The Future

Research into chronic fatigue syndrome is directed toward identifying any genetic factors that may play a role in the disorder. It is likely that CFS may be redefined as a spectrum of related disorders rather than as a single disease with a clearly identifiable cause.


Chronic : Long-term or recurrent.

Cognitive : Pertaining to thinking, learning, or memory.

Diagnosis of exclusion : A diagnosis that the doctor arrives at by ruling out other diseases one by one rather than making the diagnosis on the basis of laboratory tests or imaging studies, or other test results.

Fatigue : A feeling of weariness or tiredness after work, exercise, or emotional stress.

SEE ALSO Fibromyalgia; Lyme disease; Rheumatoid arthritis

For more information


Bested, Alison C., and Alan C. Logan. Hope and Help for Chronic Fatigue Syndrome and Fibromyalgia. Nashville, TN: Cumberland House Publishing, 2006.

Dougherty, Karla C., and Susan Lisman. Chronic Fatigue Syndrome for Dummies. Indianapolis, IN: Wiley Publishing, Inc., 2007.


Centers for Disease Control and Prevention (CDC). Chronic Fatigue Syndrome. Available online at (updated May 9, 2006; accessed May 11, 2008).

Mayo Clinic. Chronic Fatigue Syndrome. Available online at (updated June 22, 2007; accessed May 11, 2008).

TeensHealth. Chronic Fatigue Syndrome. Available online at (updated April 2007; accessed May 11, 2008).

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