What is ME?

Myalgic Encephalomyelitis (ME) is a systemic neuroimmune condition characterized by post-exertional malaise (a severe worsening of symptoms after even minimal exertion). It causes dysregulation of both the immune system and the nervous system. The effects of ME are devastating enough to leave 25% of patients housebound or bedbound. For moderate to severe patients, living with ME is like living with late-stage cancer, advanced stage AIDS, or congestive heart failure for decades.

In many parts of the world, it is commonly called Chronic Fatigue Syndrome.


It is estimated that at least 1,000,000 Americans, 250,000 British people, 100,000 Australians, and 400,000 Canadians have ME. An estimated 75-85% of them are women and 80-90% of them are undiagnosed.

*Estimates vary depending on the diagnostic criteria used.


There is no unified definition or diagnostic criteria for ME. Common symptoms include significant physical or mental fatigue, post-exertional malaise (a perverse response to normal exertion), debilitating pain, sleep dysfunction, cognitive dysfunction, neurological impairment, sensory sensitivity and severe immune dysfunction. The majority of ME patients also have postural orthostatic tachycardia (POTS).


There is no single laboratory test that can diagnose ME. Patients have consistent biological abnormalities demonstrated in research settings. Many specialist physicians use these tests to aid in forming a diagnosis, although the diagnosis is at present most frequently made by excluding other conditions that cause similar symptoms and by using one of several diagnostic criteria. Due to lack of education and awareness about ME, many patients are undiagnosed, misdiagnosed with other conditions, or told that their severe disabilities are imagined.


There is no FDA approved treatment for ME. The CDC and other agencies acknowledge treating the disease is complicated by the unknown cause. Because many ME patients’ symptoms vary over time, specialists often suggest treatments that are highly personalized and change treatment protocols frequently.

Name and Definition

ME is often called CFS (Chronic Fatigue Syndrome) or SEID (Systemic Exertion Intolerance Disease). There are differing views among patients and experts as to the correct terminology and definition of the disease.


Forgotten Plague – About ME/CFS
Myalgic encephalomyelitis: International Consensus Criteria
Canadian Concensus – A Clinical Case Definition and Guidelines for Medical Practictioners
Institute of Medicine – Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness
Primer for Clinical Practitioners – International Association for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis