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What is M.E.?

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Myalgic Encephalomyelitis (M.E.) is a long-term (chronic), fluctuating, neurological condition that causes symptoms affecting many body systems, more commonly the nervous and immune systems. M.E. affects an estimated 250,000 people in the UK, and around 17 million people worldwide.

People with M.E. experience severe, persistent fatigue associated with post-exertional malaise, the body’s inability to recover after expending even small amounts of energy, leading to a flare-up in symptoms.

Not everyone will experience the exact same symptoms so it's important not to compare someone who has M.E. to another person who has the illness. People with M.E. can vary enormously in their experience of the illness, and also how long their symptoms last. Some make good progress and may recover, while others can remain ill for a number of years and may not get better. Some people find that they don’t go back completely to the way they felt before they became ill, but they do recover sufficiently to lead happy and fulfilling lives. This is similar to many other chronic illnesses.

This section gives you more information about M.E., including possible causes and sub-groups within the condition.

What does M.E. feel like?

Sam tells us:

“It’s like having glandular fever, taking your glandular fever on an all-night drinking binge, then taking your glandular fever and your hangover and doing a 30km forced march over the Brecon Beacons. The way you would feel at the end of that is how it feels to have M.E. every day. It is like being on a carousel: you have ups and downs but you can never get off.”

Another Action for M.E. supporter says:

“I feel like I wake up with a mattress on me most mornings. When I wake up with post-exertional malaise, there is an elephant sitting on the mattress. He stays there for days. He steals my words and fills my brain with wet cotton wool and wraps his trunk around my neck, so I struggle to swallow.”

Degrees of severity

The National Institute for Health and Care Excellence (NICE) acknowledges that the physical symptoms of M.E. can be as disabling as multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, congestive heart failure and other chronic conditions.

The NICE guideline for M.E. outlines three levels of severity – mild, moderate and severe – as follows:

  • People with mild CFS/M.E. are mobile, can care for themselves and can do light domestic tasks with difficulty. Most are still working or in education, but to do this they have probably stopped all leisure and social pursuits. They often take days off, or use the weekend to cope with the rest of the week.
  • People with moderate CFS/M.E. have reduced mobility and are restricted in all activities of daily living, although they may have peaks and troughs in their level of symptoms and ability to do activities. They have usually stopped work, school or college and need rest periods, often sleeping in the afternoon for one or two hours. Their sleep at night is generally poor quality and disturbed.
  • People with severe CFS/M.E. are unable to do any activity for themselves, or can carry out minimal daily tasks only (such as face washing, cleaning teeth). They have severe cognitive difficulties and depend on a wheelchair for mobility. They are often unable to leave the house, or have a severe and prolonged after-effect if they do so. They may also spend most of their time in bed, and are often extremely sensitive to light and noise.

Even in its so-called mildest form, M.E. can have a significant impact on an individual’s life, and not just on their health. A lack of understanding and awareness about M.E. means patients can experience disbelief, and even discrimination, from friends, family, health and social care professionals and employers. 

Living with M.E. can have a great emotional and financial impact on the life of the person affected. If you're feeling isolated you can register for our free M.E. Friends Online Forum and if you're worried about the financial implications of living with M.E. you can contact our Welfare Advice and Support Service for free, confidential advice. 

Chronic fatigue syndrome (CFS)

Within the NHS, a diagnosis of chronic fatigue syndrome (CFS) or CFS/M.E. is often given. M.E. is also sometimes diagnosed as Post-Viral Fatigue Syndrome (PVFS). This can make it confusing for many.

In February 2015, the Institute of Medicine in the United States recommended changing the name to systemic exertion intolerance disease, or SEID. This has not been universally adopted. 

Action for M.E. uses the terms M.E., CFS and M.E./CFS because we do not wish to withhold support from those who have been given a diagnosis of CFS, as opposed to M.E. We recognise that it is quite possible that M.E./CFS may be an umbrella term for a number of illnesses. Therefore, it is critical that there is more biomedical research to further investigate and validate our understanding and increase knowledge of the different sub-groups (phenotypes) of M.E. and/or CFS. 


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What is M.E.?