U.S. ME/CFS Clinician Coalition








Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic, complex, debilitating, multi-system illness affecting more than one million Americans and millions worldwide. ME/CFS affects persons of both sexes and all ages, ethnicities, nationalities, genders, and socioeconomic backgrounds. It is more common in women than men and more common in adults than children.


The majority of people with ME/CFS report an infection or flu-like symptoms upon onset of their illness, but other sudden, precipitating events have also been reported. Onset may also be gradual without experiencing a notable precipitating event of any kind. The exact cause of this multi-system illness has not been definitively established, but research supports involvement of the central, peripheral, and autonomic nervous systems, aberrant immune activation and dysfunction, and abnormal and impaired cellular metabolism.

Patients experience a substantial reduction in their daily functioning and can experience a broad range of symptoms including profound fatigue, post-exertional malaise, unrefreshing and disordered sleep, cognitive impairment, orthostatic intolerance, flu-like symptoms, sensory sensitivity, amplified pain, recurrent headaches, and gastrointestinal disturbances.

The hallmark and defining feature of the illness is “post-exertional malaise” or PEM. Patients experiencing PEM will often describe a “crash,” “relapse,” or “collapse” after even small amounts of mental or physical exertion that was previously tolerated. During the crash, which may be immediate but more often delayed by hours or days, patients can experience an exacerbation of one or all of their symptoms and a further reduction in functioning. It can take hours, days, a week or even longer to return to their previous baseline after a crash. Some patients may go through cycles of overexerting and crashing while others may have learned to reduce or change activities to minimize crashes. For some patients, even basic activities of daily living can result in PEM.

Long COVID and ME/CFS:

In September 2020, Dr. Anthony Fauci of the National Institutes of Health noted that some COVID “Long Haulers,” those sick for weeks and months following an acute COVID infection, have symptoms that are “highly suggestive” of ME/CFS. In an October 2020 Clinician Coalition letter, we noted the potential for ME/CFS to develop following COVID. Since then, the intersection of ME/CFS and Long COVID has become even clearer. This highlights the need for clinicians to consider a diagnosis of ME/CFS in those with Long COVID, particularly when post-exertional malaise (PEM) is present. Early diagnosis and management of PEM and ME/CFS in these patients can help reduce patient suffering and improve quality of life. For more information, read the 2023 ME/CFS Clinician Coalition Letter.

Severity of ME/CFS as a chronic illness


ME/CFS is often more functionally debilitating than a number of other chronic diseases including rheumatoid arthritis, major depression, congestive heart failure, chronic obstructive pulmonary disease, stroke, and many malignancies, an assertion supported by data from validated SF-36 disability analysis in all of these conditions. As many as 75% of patients with ME/CFS become unable to work and an estimated 25% of patients become home-bound or even bed-bound. The most severely ill require assistance with the most basic activities of daily living including toileting and eating.

Little research has been done on the natural progression of ME/CFS but it appears that over time and without proper diagnosis and treatment, some patients will improve, some will stay the same, and some will worsen. Many patients have reported experiencing an unpredictable waxing and waning of their disease. Based upon limited studies, the rate of complete recovery appears to be very low. However, while there is no cure, medical providers can help to significantly reduce the burden of symptoms and improve a patient’s functioning and overall quality of life using some of the approaches described on this site. Even with these approaches, patients may experience relapses, requiring an adjustment to the management plan as needed.


Historically, as many as 90% of ME/CFS patients could remain undiagnosed for years and even decades, often mistaken for having other illnesses, particularly anxiety and depression, or even no illness at all. Furthermore, others have been labeled as having “chronic fatigue” without further investigation into the underlying cause. Worse still, many in the medical community have incorrectly asserted that the disabilities associated with ME/CFS were merely the result of “deconditioning,” “psychological trauma,” and/or a “fear of activity” that would be best treated by graded exercise therapy (which usually exacerbated the severity of the illness, sometimes permanently) and/or cognitive behavioral therapy.

A landmark 2015 report from the US National Academy of Medicine and a plethora of recent scientific publications have since countered those views and have provided broad and far-reaching scientific evidence for the biophysiological underpinnings and multi-system involvement of this debilitating illness. In an effort to improve the accuracy of clinical diagnosis, the 2015 National Academy of Medicine report also established new clinical diagnostic criteria centered around the hallmark symptom of post-exertional malaise.


Currently, there are no definitive laboratory tests or imaging modalities that can pinpoint a diagnosis of ME/CFS, though clinicians are able to rely upon the 2015 US National Academy of Medicine criteria for establishing an accurate diagnosis. Moreover, there are no FDA-approved treatments specifically for the management of ME/CFS.

Despite these limitations, medical providers can profoundly impact the lives of those suffering from ME/CFS by validating the existence and pathophysiological underpinnings of their illness; by teaching patients how to “pace” their physical and cognitive activities so as to avoid the complications of post-exertional malaise; by treating and mitigating symptoms of orthostatic intolerance, disordered sleep, cognitive dysfunction, pain, and other symptoms; by managing their multiple comorbidities; and by assisting patients in accessing needed support services, devices, and benefits. This site contains information designed to support medical providers in providing the best care possible for those suffering from ME/CFS.


You will find additional information regarding ME/CFS clinical management, medical education and other topics on this website.