What is ME?

ME/CFS is an illness affecting many different parts of the body, and which can last for a long time in some people.

The main symptoms are:

  • Intense fatigue and a feeling of being unwell (post-exertional malaise) that is not improved by rest, and can be worse after physical or mental effort;
  • Pain in the muscles or joints;
  • Problems in the stomach or intestine;
  • Difficulty sleeping; and
  • Memory or concentration problems (cognitive dysfunction).

Other less-common symptoms include headaches, sore throat and difficulties with vision.

Different people experience different combinations of these symptoms, and they can also vary in severity between individuals.

Unlike the tiredness experienced by healthy people, the fatigue associated with ME/CFS can happen after even mild or moderate effort, and may occur hours or days afterwards.

There have been many names given to the illness over the years, but at the moment the most widely recognised are myalgic encephalomyelitis (ME) and, separately, chronic fatigue syndrome (CFS). Each has a separate history and differences in main symptoms. However, many healthcare systems, healthcare professionals and researchers commonly use the term ME/CFS – and that is why many charities do so also.

It is important to remember that differences in the name do not change the lived experiences of those affected by illness.

ME and CFS are recorded separately by the World Health Organisation, with both being classified as diseases of the nervous system.

What is the cause?

The cause of ME/CFS is not yet known.

In some people the illness develops gradually over months or years, while in others it appears to be triggered by a viral or bacterial infection.

Herpesviruses, enteroviruses and Q fever have all been suggested as possible triggers of ME/CFS. More recently, people with chronic illness following COVID-19 have reported symptoms similar to those associated with ME/CFS.

One important question is why ME/CFS happens in some people but not in others, and research studies continue to look for differences in the genes that may explain this.

Living with ME/CFS

ME/CFS affects an estimated 250,000 people in the UK and over one million people in the USA – this is more than the number with HIV infection or multiple sclerosis.

The physical symptoms vary in severity between individuals, but can be as disabling as multiple sclerosis, congestive heart failure and other chronic conditions.

The course of the illness can also be variable: some people improve quite quickly, while others develop chronic illness lasting many years.

The illness touches all social groups and all ages, including children, and women are more likely than men to be affected.

ME/CFS can a have a big impact on a person’s ability to carry out normal activities, including everyday tasks, keeping a job, going to school, and taking part in family and social life.

Many people with ME/CFS are unable to work fulltime, and up to a quarter are house- or bed-bound.

How is ME/CFS diagnosed?

A positive diagnosis of ME/CFS can only be made by a suitably qualified medical practitioner such as a GP or hospital consultant.

In the UK, most people seeing a doctor in the NHS are diagnosed using the NICE guideline.

As there is no specific laboratory test for ME/CFS, a diagnosis is based on a person’s medical history and pattern of symptoms. Importantly, other diseases that cause similar symptoms must be ruled out before ME/CFS can be diagnosed. Unfortunately, misdiagnosis is common.

According to the NICE guideline, ME/CFS can be suspected if ALL of the following conditions are met:

  • a person has had persistent symptoms (listed below) for at least 6 weeks in adults, and 4 weeks in children and young people, and
  • the person’s ability to engage in occupational, educational, social or personal activities is significantly reduced from pre‑illness levels, and
  • the symptoms are not explained by another condition.

ALL of the following symptoms should be present to suspect ME/CFS:

  • Debilitating fatigue that is worsened by activity, is not caused by excessive cognitive, physical, emotional or social exertion, and is not significantly relieved by rest.
  • Post-exertional malaise after activity in which the worsening of symptoms:
    • is often delayed in onset by hours or days
    • is disproportionate to the activity
    • has a prolonged recovery time that may last hours, days, weeks or longer.
  • Unrefreshing sleep or sleep disturbance (or both), which may include:
    • feeling exhausted, feeling flu-like and stiff on waking
    • broken or shallow sleep, altered sleep pattern or hypersomnia.
  • Cognitive difficulties (sometimes described as ‘brain fog’), which may include problems finding words or numbers, difficulty in speaking, slowed responsiveness, short-term memory problems, and difficulty concentrating or multitasking.

Other symptoms can also be associated with, but are not exclusive to, ME/CFS:

  • orthostatic intolerance and autonomic dysfunction, including dizziness, palpitations, fainting, nausea on standing or sitting upright from a reclining position
  • temperature hypersensitivity resulting in profuse sweating, chills, hot flushes, or feeling very cold
  • neuromuscular symptoms, including twitching and myoclonic jerks
  • flu-like symptoms, including sore throat, tender glands, nausea, chills or muscle aches
  • intolerance to alcohol, or to certain foods and chemicals 
  • heightened sensory sensitivities, including to light, sound, touch, taste and smell
  • pain, including pain on touch, myalgia, headaches, eye pain, abdominal pain or joint pain without acute redness, swelling or effusion.

What treatments are available?

There is not yet any treatment that can cure ME/CFS.

Until a cure is found, there are a number of approaches that can help people manage their illness, although it is very important that these are discussed with a GP beforehand.

Drug treatments are available for some of the specific symptoms of ME/CFS, such as sleep disturbances, pain, headaches, abdominal symptoms and balance disorders.

Many people with ME/CFS find that managing their activity – by pacing or other methods – helps them to live with the illness day to day, and a variety of coping strategies are available that can make a real difference.

None of us at ME Research UK are medically qualified, and so we are not in a position to offer any specific advice or help on treatments.

The role of ME Research UK

ME Research UK exists to fund high-quality biomedical research into ME/CFS – to find its cause, to develop effective treatments, and ultimately to discover a cure.

Thanks wholly to the support of donors, to date we have provided over £2 million of funding for more than fifty research projects around the world, but there is still much more to do.

If you would like to help support further research into ME/CFS, please consider fundraising for ME Research UK or making a donation to the charity, so that we can continue to inform, influence and invest in ME research.

More information about ME/CFS

For a more detailed explanation of ME/CFS, its symptoms and treatment, we recommend the website of the US Centers for Disease Control and Prevention.