Chronic Fatigue Syndrome

Also known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) or systemic exertion intolerance disease (SEID)

Chronic fatigue syndrome is a condition that generally involves deep fatigue, unrefreshing sleep, exercise intolerance, and neurological issues referred to as “brain fog.” The exact cause of chronic fatigue syndrome is unknown but is believed to be a combination of genetic predisposition and environmental factors. With no simple test to identify it currently available, diagnosis is based on symptoms and the exclusion of other causes. Treatment is aimed at making lifestyle changes that help alleviate the condition and relieve symptoms with medications and therapies.

Frequently Asked Questions

  • What are the symptoms of chronic fatigue syndrome?

    Symptoms of chronic fatigue syndrome often vary. According to the National Academy of Medicine, fatigue, post-exertional malaise, and sleep problems must all be present in order to diagnose the condition. In addition, a patient must be experiencing either cognitive impairment (brain fog) or a worsening of symptoms while upright (orthostatic intolerance).

  • What kind of doctor diagnoses chronic fatigue syndrome?

    Many primary care doctors will be able to diagnose chronic fatigue syndrome. They may also refer you to a doctor who is knowledgeable about or specializes in fatigue disorders, or you may choose to seek out such a practitioner yourself. Physicians who specialize in treating Lyme disease and other autoimmune disorders may also have experience treating patients with chronic fatigue syndrome.

  • What causes chronic fatigue syndrome?

    While the causes of chronic fatigue syndrome are still unclear, the condition has been linked to a number of factors, including genetics; viral or other infections; hormone, immune, or central nervous system dysregulation; stress; and exposure to toxins. Some researchers believe the condition may result from several of these factors coming together under the right conditions.

  • How long does chronic fatigue syndrome last?

    By definition, chronic fatigue syndrome persists for months or years. Recovering from it often hinges on eliminating possible causes, as well as discovering a treatment protocol tailored to your individual body, symptoms, and triggers.

Key Terms


Page Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Myalgic encephalomyelitis/chronic fatigue syndrome. Updated September 18, 2020.

  2. Centers for Disease Control and Prevention. Myalgic encephalomyelitis/chronic fatigue syndrome: IOM 2015 diagnostic criteria. Updated November 19, 2019.

  3. Natelson BH. Myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia: definitions, similarities, and differences. Clin Ther. 2019;41(4):612-618. doi:10.1016/j.clinthera.2018.12.016

  4.  Tomas C, Newton J, Watson S. A review of hypothalamic-pituitary-adrenal axis function in chronic fatigue syndrome. ISRN Neurosci. 2013;2013:784520. doi:10.1155/2013/784520

  5. McGregor NR, Armstrong CW, Lewis DP, Gooley PR. Post-exertional malaise is associated with hypermetabolism, hypoacetylation and purine metabolism deregulation in ME/CFS cases. Diagnostics (Basel). 2019;9(3):70. Published 2019 Jul 4. doi:10.3390/diagnostics9030070

  6. Goudsmit EM, Nijs J, Jason LA, Wallman KE. Pacing as a strategy to improve energy management in myalgic encephalomyelitis/chronic fatigue syndrome: A consensus document. Disabil Rehabil. 2012;34(13):1140-7. doi:10.3109/09638288.2011.635746