What is ME?

Myalgic encephalomyelitis (ME) or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), is a complex chronic disease that presents with symptoms in multiple body systems.  ME is a neurological disease according to the World Health Organization. 

Susceptibility may be genetic, but the disease is triggered by infection in the majority of patients.  ME may be severe: 75% of those affected are unable to work and 25% are homebound or bedridden. ME is a common chronic consequence of viruses, with 10-12% of those with serious infection going on to develop the disease.  An estimated 15-30 million people live with the disease worldwide.

The cardinal symptom of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion.  PEM is a flare of symptoms and/or the appearance of new symptoms after exertion, often presenting ~24 hours after the triggering event.  While PEM is often studied in relation to physical activity, cognitive overexertion or sensory overload may also initiate PEM.

People with ME experience a substantial loss of physical and/or cognitive function. The average person with ME scores as more disabled on quality of life surveys than those with multiple sclerosis, stroke, diabetes, renal failure, lung disease, heart failure, and cancer.  Someone with mild ME may be able to work full-time with accommodations; someone with very severe ME may be bedbound and have trouble communicating.

ME is a relapsing-remitting condition.  Individual patients experience significant fluctuations in their well-being from day to day, week to week, and month to month.


An estimated 15-30 million people around the world are suffering from ME including at least:


The hallmark symptom of ME is post-exertional malaise, a reduction in functioning and a severe worsening of symptoms after even minimal physical or cognitive exertion.

Other common symptoms include:

  • Sensitivity to light, sound or vibration, taste, odor or touch
  • Gastrointestinal symptoms such as nausea or abdominal pain
  • Muscle fatigability, weakness and fasciculation; poor coordination and ataxia
  • Autonomic and endocrine symptoms such as poor temperature regulation, cold or heat intolerance
  • Immune symptoms such as tender lymph nodes, recurrent sore throats, fevers, or flu-like symptoms, and new food or chemical sensitivities


While 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 sets of diagnostic criteria. Due to lack of education and awareness about ME, many patients are undiagnosed, or misdiagnosed with other conditions.


There are no approved treatments for ME. Because many ME patients’ symptoms vary over time, specialists often suggest treatments that are highly personalized.

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