Chronic fatigue syndrome (CFS) is a complicated disorder characterized by extreme fatigue that can’t be explained by any underlying medical condition. The fatigue may worsen with physical or mental activity, but doesn’t improve with rest.

This condition is also known as systemic exertion intolerance disease (SEID) or myalgic encephalomyelitis (ME). Sometimes it’s abbreviated as ME/CFS.

The cause of chronic fatigue syndrome is unknown, although there are many theories — ranging from viral infections to psychological stress. Some experts believe chronic fatigue syndrome might be triggered by a combination of factors.

There’s no single test to confirm a diagnosis of chronic fatigue syndrome. You may need a variety of medical tests to rule out other health problems that have similar symptoms. Treatment for chronic fatigue syndrome focuses on symptom relief.

Symptoms

Signs and symptoms may include:

• Fatigue
• Loss of memory or concentration
• Sore throat
• Enlarged lymph nodes in your neck or armpits
• Unexplained muscle or joint pain
• Headaches
• Unrefreshing sleep
• Extreme exhaustion lasting more than 24 hours after physical or mental exercise

When to see a doctor

Fatigue can be a symptom of many illnesses, such as infections or psychological disorders. In general, see your doctor if you have persistent or excessive fatigue.

Causes:

People who have chronic fatigue syndrome appear to be hypersensitive to even normal amounts of exercise and activity.

Why this occurs in some people and not others is still unknown. Some people may be born with a predisposition for the disorder, which is then triggered by a combination of factors. Potential triggers include:

• Viral infections. Because some people develop chronic fatigue syndrome after having a viral infection, researchers question whether some viruses might trigger the disorder. Suspicious viruses include Epstein-Barr virus, human herpes virus 6 and mouse leukemia viruses. No conclusive link has yet been found.
• Immune system problems. The immune systems of people who have chronic fatigue syndrome appear to be impaired slightly, but it’s unclear if this impairment is enough to actually cause the disorder
• Hormonal imbalances. People who have chronic fatigue syndrome also sometimes experience abnormal blood levels of hormones produced in the hypothalamus, pituitary glands or adrenal glands. But the significance of these abnormalities is still unknown.

Diagnosis:

There’s no single test to confirm a diagnosis of chronic fatigue syndrome. Because the symptoms of chronic fatigue syndrome can mimic so many other health problems, you may need patience while waiting for a diagnosis.

Your doctor must rule out a number of other illnesses before diagnosing chronic fatigue syndrome. These may include:

• Sleep disorders. Chronic fatigue can be caused by sleep disorders. A sleep study can determine if your rest is being disturbed by disorders such as obstructive sleep apnea, restless legs syndrome or insomnia.
• Medical problems. Fatigue is a common symptom in several medical conditions, such as anemia, diabetes and underactive thyroid (hypothyroidism). Lab tests can check your blood for evidence of some of the top suspects.
• Heart and lung impairments. Problems with your heart or lungs can make you feel more fatigued. An exercise stress test can assess your heart and lung function.
• Mental health issues. Fatigue is also a symptom of a variety of mental health problems, such as depression, anxiety, bipolar disorder and schizophrenia. A counselor can help determine if one of these problems is causing your fatigue.

Treatment:

There is no cure for chronic fatigue syndrome. Treatment focuses on symptom relief.

Medications

Many people who have chronic fatigue syndrome are also depressed. Treating your depression can make it easier for you to cope with the problems associated with chronic fatigue syndrome. Low doses of some antidepressants also can help improve sleep and relieve pain.

Therapy

The most effective treatment for chronic fatigue syndrome appears to be a two-pronged approach that combines cognitive training with a gentle exercise program.

• Cognitive training. Talking with a counselor can help you figure out options to work around some of the limitations that chronic fatigue syndrome imposes on you. Feeling more in control of your life can improve your outlook dramatically.
• Graded exercise. A physical therapist can help determine what exercises are best for you. Inactive people often begin with range-of-motion and stretching exercises for just a few minutes a day. Gradually increasing the intensity of your exercise over time may help reduce your hypersensitivity to exercise, just like allergy shots gradually reduce a person’s hypersensitivity to a particular allergen.

Risk factors

Factors that may increase your risk of chronic fatigue syndrome include:

• Age. Chronic fatigue syndrome can occur at any age, but it most commonly affects people in their 40s and 50s.
• Sex. Women are diagnosed with chronic fatigue syndrome much more often than men, but it may be that women are simply more likely to report their symptoms to a doctor.
• Stress. Difficulty managing stress may contribute to the development of chronic fatigue syndrome.

Complications:

Possible complications of chronic fatigue syndrome include:

• Depression
• Social isolation
• Lifestyle restrictions
• Increased work absences