IOM Definition for ME/CFS (2015)


In early 2015, a committee commissioned by the Institute of Medicine (now called the National Academy of Medicine) recommended a new clinical definition for ME/CFS.

The committee’s report was released in a lengthy document entitled Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness.

The committee also recommended changing the name of the disease to SEID (systemic exertion intolerance disease).


Read the Article

Read the Clinicians’ Guide


Proposed Diagnostic Criteria for ME/CFS

Diagnosis requires that the patient have the following three symptoms:

1. A substantial reduction or impairment in the ability to engage in pre-illness levels of occupational, educational, social or personal activities, that persists for more than six months and is accompanied by fatigue, which is often  profound, is of new or definite onset (not lifelong), is not the result of ongoing excessive exertion, and is not substantially alleviated by rest.

2. Post-exertional malaise* and

3. Unrefreshing sleep*

At least one of the two following manifestations is also required:

1. Cognitive impairment* or

2. Orthostatic intolerance


* Frequency and severity of symptoms should be assessed. The diagnosis of ME/CFS should be questioned if patients do not have these symptoms at least half the time with with moderate, substantial or severe intensity.


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