Chronic fatigue syndrome (CFS) is a complex condition that causes chronic, debilitating fatigue that is not relieved by bed rest or explained by any other medical condition. People who have CFS perform at a significantly lower level compared to their activity prior to the onset of the illness.


The exact cause of CFS is unknown. Some theories have associated the development of CFS with an infection, though a specific infectious agent has not been identified. Other research has suggested possible associations with abnormalities in the immune, endocrine, and/or nervous systems. CFS may be associated with a single trigger that has yet to be identified or it may be related to a combination of factors. More research may help find causes or triggers.


CFS is more common in women than men. Although CFS can happen at any age, it is generally seen in adults aged 25-55 years old. Other factors that may increase your chance of CFS include:

  • Recent history of:
    • Viral infection—examples include Epstein-Barr (causes mononucleosis), a variety of intestinal viruses, rubella (German measles), or Ross River fever (transmitted by mosquitoes in the tropics)
    • Fungal infection—examples include some yeast infections
    • Bacterial infection—examples include atypical pneumonia and Q fever
  • Family history of CFS
  • Suppressed immune system
  • Chronic stress
  • Problems with autoimmunity—abnormal immune response to healthy body tissues
  • Allergies or sensitivities to foods, chemicals, odors, medications, light, or noise
  • Exposure to toxins
  • Trauma


Symptoms vary from person to person. They may include:

  • Unexplained, new onset, persistent fatigue that is not relieved with bed rest and often worsens with physical or mental activity
  • Unexplained muscle aches
  • Joint pain without swelling or redness over 6 months
  • Headaches over 6 months
  • Trouble with short-term memory or concentration
  • Forgetfulness or confusion
  • Irritability, anxiety, panic attacks, mood swings, or depression
  • Sore throat over 6 months
  • Tender lymph nodes over 6 months
  • Trouble sleeping or not feeling refreshed after sleep over 6 months
  • Visual problems, such as blurring or eye pain
  • Reduced activities—social, job-related, educational, and personal
  • Lightheadedness, balance problems, or fainting
  • Chills and night sweats


You will be asked about your symptoms and medical history. A physical exam will be done. There are no specific diagnostic tests for CFS. Your doctor may do several other tests to rule out other conditions that can have similar symptoms. Blood, urine, and imaging tests generally appear normal, even when symptoms are present.

CFS diagnosis is a process of elimination. It may take a long time for CFS to be diagnosed. CFS may be diagnosed if there are no signs of other medical conditions, tests reveal nothing out of the ordinary, and the following criteria exist:

  • Severe, chronic fatigue for at least 6 months that is not due to exertion, or other illness or medical cause AND
  • Fatigue interferes with daily activities like work or school AND
  • At least 4 of the following:
    • Impairment of short-term memory or concentration
    • Sore throat that keeps coming back
    • Tender lymph nodes in the neck or armpit
    • Muscle pain
    • Joint pain without swelling or redness
    • Headaches of a new type, severity, or pattern
    • Unrefreshing sleep
    • Prolonged fatigue lasting 24 hours or more after exercise


There is no cure for CFS, but its symptoms can be managed with the goal of improving the quality of life. Some treatments will work better for some than others. A combination of approaches may also be most effective.

Physical activity

If you have CFS, avoid overexertion and physical and emotional stress. Balancing your activities throughout the day may help you to not overexert yourself. Moderate exercise that is monitored by a doctor or physical therapist may improve symptoms. Slowly increase the duration and intensity of exercise. Light exercise and stretching 4 hours before bedtime may help with sleep.

In addition, your doctor may have you work with a physical therapist. Some therapies that might be helpful for you include:

Diet and nutrition

A well-balanced diet can help prevent nutritional deficiencies and weight fluctuations. Nutritional supplements cannot make up for a poor diet. Avoid foods to which you may be sensitive.


CFS can be mentally and physically debilitating. Depression is common among people with CFS. In fact, as many as half develop depression as a consequence of CFS. Psychotherapy and supportive counseling often help those with CFS cope with the disorder. Learning relaxation training and stress management techniques, as well as changing your sleep routine, may also help.

Talk with your therapist about whether cognitive-behavioral therapy (CBT) is right for you to reduce fatigue symptoms. CBT is a problem-solving therapy that helps you change the way you perceive and react to situations, especially ones beyond your control.


Medications used to treat specific symptoms of CFS include:

  • Antidepressants
  • Anti-anxiety medications
  • Over-the-counter medications, such as ibuprofen and acetaminophen
  • Stimulants—mild ones may be helpful
  • Sedatives—to help with insomnia


There are no current guidelines to prevent CFS because the cause is unknown.