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What is

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a life-altering multi-system chronic, complex disease (msCCD). 

Over 20 million people

have ME/CFS worldwide

1 - 2.5 million

are affected in the USA alone

Estimated 70% cannot work

25% are homebound

No diagnostic test

No FDA approved treatment
No cure

Huge economic burden

36-51 billion dollars
per year in the USA

ME / CFS affects

men, women and children.
Anyone. Any time.

A life altering disease

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a complex multi-system disease with many symptoms that may change over time and differ from patient to patient. The most common symptoms of ME/CFS are post-exertional malaise (worsening of symptoms upon even minimal exertion), unrefreshing sleep, profound fatigue, cognitive impairment, orthostatic intolerance, and pain.

The cause of ME/CFS is currently unknown, but a combination of genetic and environmental factors appear to be relevant. There are no specific diagnostic tests or FDA approved treatments available.

ME/CFS is a multi-system disease


Not only do symptoms vary in type but also in severity, ranging from mild to severe. An estimated one in four patients are housebound or bed bound and many of the most severely affected need to be fed by tube.

There are over 60 symptoms reported by people with ME/CFS. The common symptoms are listed but not limited to what may define an individual experience.

Currently, there is no laboratory diagnostic test. Due to a symptom set that overlaps with several other diseases, clinical assessment and symptoms and the exclusion of other diseases are necessary for accurate diagnosis.

Most Common Symptoms

Main Diagnostic Symptoms

Post-exertional malaise (PEM) - symptoms worsen after exertion

Reduction or impairment in ability to carry out normal daily activities, accompanied by Profound Fatigue

Unrefreshing sleep

Cognitive Impairment

Orthostatic intolerance (symptoms worsen when sitting or standing upright)

Severe body pain and worsening headaches

Neurological or Cognitive Symptoms

Brain Fog

Confusion & Disorientation

Difficulty concentrating

Short-term memory issues

Ataxia and muscle weakness

Hypersensitivity to noise and light

Autonomic, Immune & Digestive Symptoms

Postural Orthostatic Tachycardia Syndrome (POTS)


Irregular heartbeat

Increased heart rate on standing

Recurrent flu-like symptoms

Sweating, fever, chills and night sweats

Nausea & Irritable Bowel Syndrome

New sensitivities to food, medication, chemicals

Recurring sore throat

Joint pain without swelling or redness

Tender lymph nodes


Shortness of breath

Change in body weight

Temperature instability

Change in appetite

People with ME/CFS often go years before diagnosis, and 90% of sufferers have never been properly diagnosed.


You play a vital role in helping healthcare providers understand your symptoms (or your family member’s symptoms) and how they affect your daily life. Open Medicine Foundation hopes to empower you to take care of your health today, while we search for answers for tomorrow.

helpful resources

What's it going to take to eradicate this disease?


Today, the landscape of Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME / CFS) research is growing with the outlook for people with ME/CFS brighter than ever.

The End ME/CFS Project encompasses OMF funded and facilitated research conducted at six ME/CFS Collaborative Research Centers (CRCs) across the globe. OMF’s guiding strategy focuses on open, collaborative research so that precise diagnostic tools and life-changing treatments can be available to people with ME/CFS and related chronic complex diseases as soon as possible.

Support Open Medicine Foundation’s quest to find effective treatments and diagnostic tests for the millions of people affected by ME/CFS!

The End ME/CFS Project logo

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ME/CFS and Long COVID fact sheet

Pensive man leaning on a table. What is ME/CFS Fact sheet

Perfect for printing and sharing with your doctor or personal community.

Support OMF

Support Open Medicine Foundation’s quest to find effective treatments and diagnostic tests for the millions of people affected by these devastating diseases!

Disclaimer: This website is for informational purposes only. The information provided on this website is not intended to be a substitute for professional medical advice, diagnosis, or treatment.

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Read more about the diagnostic criteria
Myalgic Encephalomyelitis / Chronic Fatigue Syndrome (ME / CFS) Post Treatment Lyme Disease Syndrome (PTLDS), Fibromyalgia Leading Research. Delivering Hope.Open Medicine Foundation®

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