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Chronic Fatigue Syndrome

Chronic fatigue syndrome (CFS) is a disorder that causes persistent, unexplained extreme tiredness. The disorder is also known as myalgic encephalomyelitis.

It can be difficult to diagnose CFS. The symptoms can be debilitating but are common to many other diseases. There are no specific diagnostic tests for CFS.

Living with this condition can be frustrating because there is no targeted therapy for CFS. Currently, the management of CFS focuses on symptom management.


The cause of chronic fatigue syndrome is not known. It is thought that some people may be genetically predisposed to developing CFS and the disorder is triggered by a combination of factors. These factors include:

  • Viral infection. Some people with CFS develop the disorder after recovering from a viral infection such as Epstein-Barr virus infection or Lyme disease.

  • Immune disorder. People with CFS are not at increased risk for opportunistic infections. The immune system appears to be functional but slightly weakened in those with CFS compared to asymptomatic controls.

  • Nervous system disorder. Research suggests that some people with CFS have low blood pressure caused by nervous system dysfunction.


Although the underlying cause of chronic fatigue syndrome has not been identified, doctors understand that the syndrome and its symptoms are real. These symptoms include:

  • Fatigue

  • Worsening of symptoms after certain stressors such as physical exertion (post-exertional malaise)

  • Worsening of symptoms with standing and maintaining an upright posture (orthostatic intolerance)

  • Unrefreshing sleep

  • Memory and concentration problems

  • Aching joints

  • Aching muscles

  • Nausea

  • Sore throats

  • Headaches

CFS can be unpredictable. The symptoms may come and go and can change over time.


The diagnosis of chronic fatigue syndrome is based on medical history, symptoms, and physical exam. It is a difficult diagnosis to make. There are no lab tests for it. Other diseases with the same or similar features must be ruled out before making a diagnosis of CFS.

The diagnosis of CFS requires the exclusion of other diseases and the presence of the following symptoms for at least six months with moderate, substantial, or severe intensity:

  • Persistent fatigue

  • Post-exertional malaise

  • Unrefreshing sleep

  • Memory and concentration problems

  • Orthostatic intolerance


Currently, there is no cure or specific treatment for chronic fatigue syndrome. Treatment is focused on symptom relief. Patients need to work with their healthcare team to develop a treatment strategy that includes drug and non-drug therapies.

For people who are able to tolerate it, continuing to be physically active is likely to be helpful. The goal is to remain active without overdoing it.

Living with chronic fatigue syndrome can be exhausting and frustrating. In addition to having a strong relationship with an experienced health care provider, it may be helpful to talk to a counselor to build coping skills to deal with this chronic illness.


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