Frequently Asked Questions

What is ME/CFS?

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), sometimes referred to as myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS), is a debilitating disease that lacks a universally accepted case definition, cause, diagnosis, or treatment. According to the CDC, more than one million Americans may have ME/CFS. At least one-quarter of individuals with ME/CFS are bedbound or housebound at some point during the illness and most never regain their pre-disease level of functioning. ME/CFS strikes people of all ages and racial, ethnic, and socioeconomic groups, and is diagnosed two to four times more often in women.

The disease is characterized by at least six months of incapacitating fatigue experienced as profound exhaustion and extremely poor stamina, and problems with concentration and short-term memory. It is sometimes preceded by flu-like symptoms followed by pain in the joints and muscles, unrefreshing sleep, tender lymph nodes, sore throat, and headache. A distinctive characteristic of the illness is post-exertional malaise (PEM), which is a worsening of symptoms following physical or mental activity occurring within 12-48 hours of the exertion and requiring an extended recovery period. Although the cause of ME/CFS remains unknown, symptoms may be triggered by an infection.

Learn more about ME/CFS.

What is the difference between chronic fatigue (as a symptom) and ME/CFS?

Fatigue is a term used to describe an overall feeling of tiredness or lack of energy. It isn't the same as simply feeling drowsy or sleepy. When you're fatigued, you have low motivation and low energy. Being sleepy may be a symptom of fatigue, but it's not the same thing. If fatigue persists over a long period of time it is termed chronic fatigue. ME/CFS is distinct from chronic fatigue because there are several additional symptoms that are not seen in an otherwise healthy person who has chronic fatigue.

ME/CFS symptoms vary from one individual to another, but may include:

  • Extreme exhaustion, which is made worse by physical or mental effort—this symptom, called post-exertional malaise (PEM) is unique to ME/CFS.
  • Nonrestorative sleep
  • Brain fog/cognitive impairment
  • Joint pain
  • Inflamed lymph nodes
  • Persistent sore throat
  • Severe headache
  • Neurological abnormalities
  • Complete organ system shutdown
  • Sensitivity to light, sound, odors, chemicals, foods, and medications

Because these symptoms are shared with many other illnesses—and because many of these conditions lack a diagnostic test or biomarker—identifying which illnesses are present can be difficult. Some individuals receive diagnoses for multiple conditions. Common conditions that occur along with ME/CFS (co-morbidities) include the following:

  • Fibromyalgia
  • Orthostatic intolerance
  • Postural Orthostatic Tachycardia Syndrome (POTS)
  • Irritable bowel syndrome
  • Interstitial cystitis
  • Temporomandibular joint disorder
  • Chronic pelvic pain
  • Multiple chemical sensitivity disorder
  • Ehlers-Danlos Syndrome

What is post-exertional malaise (PEM)?

Post-exertional malaise (PEM) is an exacerbation of some or all of an individual's ME/CFS symptoms that occurs after physical or cognitive exertion and leads to a reduction in functional ability (Carruthers et al., 2003).

How is ME/CFS diagnosed?

Although challenging, experienced clinicians recognize and are able to make the diagnosis of ME/CFS. Visit the CDC to learn more about how ME/CFS is diagnosed.

Are there support services for individuals with ME/CFS, their families, and caregivers?

Individuals with ME/CFS, their families, and caregivers may contact Solve ME/CFS Initiative ( and ME Action ( for information and support.

What are the main avenues of research in the ME/CFS Collaborative Research Centers?

The three ME/CFS Collaborative Research Centers at Columbia University in New York City, Cornell University in Ithaca, NY and Jackson Laboratories in Farmington, CT are funded by the National Institutes of Health (NIH). The research at the three Centers is focused on identifying the underlying cause(s) of ME/CFS. All of the Centers are interested in the impact of the disease on individuals, how and why the symptoms become worse and/or change following exercise or demanding mental activity, and over time identify possible biomarkers that can help health care providers to diagnose ME/CFS as well as be used to track progression of disease and response to treatment.

Information about the specific research being conducted at each of the ME/CFS Collaborative Research Centers may be found here:



Jackson Laboratory

What is the role of the Data Management Coordinating Center?

The Data Management Coordinating Center (DMCC), housed at RTI, facilitates and coordinates the research activities carried out at the three Collaborative Research Centers. The Center provides support for infrastructure, data management, and outreach to the community and ME/CFS stakeholders.

What makes ME/CFS research challenging?

ME/CFS research is challenging for several reasons:

  • There is a need for more researchers to focus on ME/CFS to expand the scope of research on this disease.
  • The symptoms of ME/CFS can vary from one individual to another and in a given individual from one day to the next, making it very challenging to study the disease. Researchers are exploring ways to subtype individuals with ME/CFS to get more clear answers about the cause(s) and impact of the disease.
  • Many individuals with ME/CFS have normal results on standard laboratory tests, so researchers need to develop new assays and new ways to study ME/CFS.
  • It is often difficult for individuals with ME/CFS to participate in research because of the severity of the disease.

What role does the National Institutes of Health (NIH) play in funding research into ME/CFS?

Currently, the NIH is funding $14.8 million in research on ME/CFS. This amount has increased from $5 million in 2015 and there are significant efforts underway to increase the number of investigators studying ME/CFS and the number of grant applications submitted to NIH for consideration for funding in the peer review system.

How can I participate in research on ME/CFS?

There are several ongoing studies in the ME/CFS Collaborative Research Centers that you can participate in, as well as studies at other research centers. For studies that are recruiting participants (both individuals with ME/CFS and healthy controls) in the ME/CFS Collaborative Research Centers go to:

For all ongoing clinical studies in ME/CFS, go to

Is there a registry for individuals with ME/CFS?

Solve ME/CFS Initiative, a nonprofit organization, supports a registry in which individuals with ME/CFS can register, provide their medical information, and agree to participate in research. Visit or contact them to find out how you can participate.

How does an individual with ME/CFS donate biospecimens to be used in research?

Many of the studies underway in the ME/CFS Collaborative Research Centers are collecting biospecimens and detailed clinical information from individuals with ME/CFS and healthy controls for their research. If you are interested in participating in research, contact one of the research sites:

Can I donate my body and/or brain postmortem to research?

Yes, you can donate your body and/or brain at the time of death to research. In collaboration with the Brain Donor Project (BDP), Solve ME/CFS Initiative, and the Open Medicine Foundation (OMF), the NIH NeuroBioBank has been working to promote brain donation by the ME/CFS community. As a result of these efforts, there are now more than 200 individuals with ME/CSF who have preregistered through the BDP and two registrants who have come to autopsy and been collected by the University of Maryland NeuroBioBank. This is certainly a sensitive decision but a question that Solve ME/CFS and OMF often hear from individuals with ME/CFS. If you are interested in learning more about brain donation, starting the process is easy. Just go to to get answers to your questions.

If you're ready to sign up, click on the "Sign Up" button at the top right, and complete the online form. You'll be asked for contact information and whether you've been diagnosed with a neurological condition. If you are acting on behalf of a loved one with ME/CFS, it's important to know that this must be done prior to the individual passing away.

Grants that fund MECFSnet are managed by the National Institutes of Health (NIH) National Institute of Allergy and Infectious Diseases and the National Institute of Neurological Disorders and Stroke. This website was supported by a grant from NIH, grant #U24-NS-105535.

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What is ME/CFS?

Myalgic Encephalomyelitis (ME), also referred to as Chronic Fatigue Syndrome (CFS), is a multi-system disease that causes dysfunction of the neurological, immune, endocrine, and energy metabolism systems.