Chronic Fatigue Syndrome: Symptoms & Signs

Medically Reviewed on 9/10/2019

The diagnosis of chronic fatigue syndrome (CFS) means that the sufferer has experienced fatigue for at least six months in the absence of known medical causes as well as had other characteristic symptoms. The Institute of Medicine (IOM) committee recommends the name systemic exertion intolerance disease (SEID) for this disease, and it has also been referred to as myalgic encephalomyelitis (ME), even though no evidence of inflammation of the brain (encephalitis) has been demonstrated with this condition.

Characteristic symptoms in addition to fatigue include

Other signs and symptoms may also be present, like

Dizziness, balance problems, fainting, food sensitivities, night sweats, chills, vision disturbances, mood changes, and depression have also been reported. The symptoms can be generalized and may occur due to many different causes; therefore, the diagnosis of chronic fatigue syndrome relies upon excluding other medical causes of the symptoms.

Causes of chronic fatigue syndrome

The exact cause of CFS or SEID is not known. There are no proven links to any known disease infection that is responsible for CFS or SEID development. Researchers are still trying to identify the cause(s) of CFS/SEID suggest the possibility that CFS/SEID represents an endpoint of multiple diseases or conditions such as viral infections, stress, and toxin exposure. However, the U.S. Centers for Disease Control and Prevention (CDC) states that "CFS is not caused exclusively by any single recognized infectious disease agent." This includes Epstein-Barr virus, Lyme disease bacteria (Borrelia burgdorferi), human retroviruses, Mycoplasma, and many others. Some researchers have suggested that a new virus found in some CFS/SEID patients (termed XMRV or xenotropic murine leukemia virus-related virus) may be a candidate for cause, but a larger study failed to prove this theory.

Other chronic fatigue syndrome symptoms and signs


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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.