Main Menu
Donate
Sign Up

Understanding
Myalgic Encephalomyelitis/
Chronic Fatigue Syndrome

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

20+ million worldwide

have ME/CFS (pre-Long COVID)*

3.3 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.

*An NIH-funded study found that new cases of ME/CFS were 15 times higher than pre-pandemic levels. According to the results, 4.5% post-COVID-19 participants met ME/CFS diagnostic criteria, compared to 0.6% participants that had not been infected by SARS-CoV-2 virus.  

These findings provide additional evidence that infections, including those caused by SARS-CoV-2, can lead to ME/CFS.

What is ME/CFS?

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, complex, debilitating and multi-system illness involving:

  • Brain Inflammation
  • Peripheral Nervous System
  • Immune System
  • Circulatory System
  • Cellular Metabolism

This information is provided by Lucinda Bateman, MD, director of the OMF-supported Medical Education Resource Center (MERC) at the Bateman Horne Center.

What Causes ME/CFS?

The cause of ME/CFS is currently unknown, but a combination of genetic and environmental factors appear to be relevant. There are no FDA approved treatments available.
Jump to
Symptoms
Diagnosis
Research
Resources
ME/CFS is a multi-system disease

ME/CFS Symptoms

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.

A diagram of the symptoms of ME/CFS

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)

Dysautonomia

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

Light-headedness

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.

Diagnosis

Diagnosing ME/CFS is complex, as no single test can confirm the condition. In 2015, the National Academy of Medicine (NAM), formerly called the Institute of Medicine, outlined diagnostic criteria applicable to both adults and children. 

These criteria require three core symptoms, with at least one of two additional symptoms, for a confirmed diagnosis.

Core symptoms:

  • Impairment of normal function accompanied by fatigue persisting >6 months
  • Post-exertional malaise (PEM)*
  • Unrefreshing sleep*


Plus at least one of the following:

  • Cognitive impairment*
  • Orthostatic intolerance (OI)


*Must be moderate-to-severe and present >50% of the time

Challenges in Diagnosing ME/CFS

Navigating Complex Symptoms

Diagnosing Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) presents unique challenges due to the broad and overlapping nature of its symptoms. Many symptoms, such as profound fatigue and cognitive difficulties—common to other illnesses like fibromyalgia and Lyme disease—require healthcare providers to perform careful assessments to distinguish ME/CFS from these conditions.

The Path Toward Better Diagnostic Tools

Currently, there are no specific laboratory tests for ME/CFS, underscoring the need for research and development in this area. The medical community is actively working towards refining diagnostic criteria and developing precise tools based on the latest scientific insights.

Empowering Patients and Providers

Given the variability of ME/CFS symptoms, a personalized approach to diagnosis is essential. Patients are encouraged to work closely with healthcare providers, documenting and communicating their symptoms accurately. This partnership is crucial for navigating the diagnosis process effectively and ensuring patients receive the care they need.

Video content by the OMF-supported Medical Education Resource Center (MERC) at Bateman Horne Center.

helpful resources

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

Research

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!

Read about The END ME / CFS Project
The End ME/CFS Project logo

Download the

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.

Click here to get your copy

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!

Donate now

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.

Frequently Asked Questions

Is ME/CFS contagious?

No, ME/CFS is not contagious. It cannot be spread from person to person like infectious diseases.

The progression of ME/CFS varies among individuals. Some people may experience a gradual improvement in their symptoms, while others may see their symptoms worsen or experience fluctuations in the severity of their symptoms over time. Factors such as stress, infections, or other health complications can exacerbate symptoms. Careful management of triggers and symptoms is essential to prevent exacerbations.

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) significantly impacts daily living, with profound fatigue that makes routine tasks challenging. This condition often leads to cognitive difficulties, such as memory issues and concentration problems, affecting work and social interactions. Physical symptoms like muscle pain and post-exertional malaise restrict activity levels and may necessitate days of recovery after even minor exertions. The unpredictable nature of the illness can cause social isolation, emotional distress, and financial strain due to reduced work capacity. Additionally, sleep disturbances further exacerbate daily fatigue, complicating overall management and quality of life.

Other links you might be interested in:

Foundation Team
History of ME / CFS
Facebook Twitter Youtube Instagram Linkedin

OMF is a non-profit 501(c)(3) organization
(EIN# 26-4712664). All donations are tax-deductible to the extent allowed by law.

2024 YEAR END REPORT

Open Medicine Foundation®
29302 Laro Drive,  Agoura Hills, CA 91301 USA
Phone: 650-242-8669
info@omf.ngo

Contact Us

PRIVACY  |  COOKIE   |   CONSENT   |  MEDICAL & OTHER DISCLAIMERS

Copyright © 2025 Open Medicine Foundation. All Rights Reserved.


Centers for Disease Control and Prevention (CDC)

Holmes 1988

This was the first definition put together by the CDC and the first to coin the term “chronic fatigue syndrome” (CFS). The definition required persistent fatigue along with 8 of 11 specific symptoms under the categories of short-term memory issues, pain, sleep disturbance, post-exertional malaise and flu-like symptoms. This diagnosis was very specific and hard to utilize in a clinical setting for diagnosis.
Holmes CDC 1988
Centers for Disease Control and Prevention (CDC)

Fukuda 1994

This definition is a revision of the Holmes definition except it requires half the number of symptoms to make a diagnosis. This diagnosis was much easier for clinicians and significantly increased the incidence of CFS numbers globally. It has been criticized for being too easy to misdiagnose.
Fukuda CDC 1994

Canadian Consensus Criteria (CCC) 2003

From a look at Table 1 you can see a significant change in the definitions from Holmes and Fukuda to the CCC 2003. This was the first definition to incorporate CFS with the Myalgic Encephalomyelitis (ME) definition by Dr Ramsay several decades earlier. This definition requires post-exertional malaise (PEM), fatigue, pain, sleep disturbance, a couple neurocognitive issues and symptoms from the immune, endocrine and autonomic systems. This diagnosis emphasized the multi-system component of the illness and attempted to homogenize the cohort diagnosed by requiring several specific symptoms. One of those specific symptoms, PEM, is clearly the most distinguishing feature of ME/CFS.
Canadian Consensus Criteria 2003

The improvement of research and SEID

The definition was further refined by the Institute of Medicine in 2015 to create a diagnosis that incorporated the most up-to-date research while providing a simple diagnosis in the clinical setting. The definition was a departure from all previous definitions and was therefore given a new name, Systemic Exertion Intolerance Disease (SEID). This definition is most similar to CCC in that it requires fatigue, PEM and sleep disturbance. Unlike CCC this definition only required cognitive problems or orthostatic intolerance, instead of having a broad range of symptoms to signify the multi-system component of the illness. Simplifying the diagnosis like this is beneficial to research for building cohorts around specific symptoms that are common throughout.
Institute of Medicine 2015
Receive the latest news

Collaborative research moves fast. 

Get the latest updates delivered to your inbox.

SIGN UP
Read more about the diagnostic criteria
Holmes 1988
Fukuda 1994
CCC 2003
IOM 2015
CCC 2003

International Consensus Criteria (ICC) 2011

The CCC was further developed in 2011 to form the International Consensus Criteria (ICC). This was the first modern definition to not include fatigue as a required symptom and to not require 6 months of symptoms persisting to be diagnosed. PEM is the only required symptom. As compared to the CCC definition, the ICC definition puts a greater emphasis on the multi-system component of the illness, requiring more symptoms from the immune and endocrine systems. Removing fatigue as a necessary symptom and the minimum of 6 months for diagnosis enables the differentiation of ME from CFS for considerations in research and treatment.
International Consensus Criteria 2011

Consent management

Consent Preferences

Data Subject Access Request (DSAR) Form 

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

What are the advantages of giving from your Donor Advised Fund (DAF)?

  • Your gifts to your donor advised fund entitle you to an immediate income tax deduction at the time of contribution.
  • You avoid capital gains tax on appreciated assets you place in your donor advised fund.
  • Your fund’s investment gains accumulate tax free.
  • Funds are distributed to Open Medicine Foundation in your name and immediately put to use to support our worldwide research efforts.


How do I make a donation through my DAF?

Just click on the DAF widget below. It is simple and convenient to find your fund among the over 900 funds in our system.

Still can’t find your fund? 

  • Request a grant distribution through your Donor Advised Fund sponsor
  • Be sure to use OMF’s EIN #26-4712664
  • You can also designate OMF as a beneficiary for your Donor Advised Fund
  • Questions? Give us a call at 650-242-8669 
Give now from your
Donor-Advised Fund
 
Donate