Health Topic

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a long-term illness. It causes severe fatigue and many other symptoms. Learn about managing them.

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Also called: CFS · Chronic fatigue syndrome · ME/CFS · Myalgic encephalomyelitis · SEID · Systemic exertion intolerance disease

Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.

About Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a serious, long-term illness that affects many body systems. Another name for it is chronic fatigue syndrome (CFS). ME/CFS can often make you unable to do your usual activities. Sometimes you may not even be able to get out of bed.

Researchers don't yet know what causes ME/CFS. There may be more than one potential cause. It is also possible that two or more triggers might work together to cause the illness.

Researchers are studying many possible causes, including:

  • Infections
  • Immune system changes
  • Physical or emotional stress
  • Changes in the way cells in the body get their energy
  • Genetics; the illness can sometimes run in families

Anyone can get ME/CFS, but it is most common in people between 40 and 60 years old. Adult women are more likely to develop it than adult men.

The primary, or core, symptoms of ME/CFS are:

  • Not being able to do activities that you used to do before the illness, along with severe fatigue. The fatigue must last six months or longer, and it is not improved by rest.
  • Post-exertional malaise (PEM), which means that your symptoms get worse after any physical or mental activity.
  • Sleep problems.

Along with the primary symptoms, to be diagnosed with ME/CFS, you need to have one or both of these symptoms:

  • Problems with thinking and memory.
  • Worsening of symptoms while standing or sitting upright. This is called orthostatic intolerance. It can cause you to feel lightheaded, dizzy, weak, or faint while standing or sitting up.

Some of the other symptoms that ME/CFS can cause include:

  • Pain, including muscle pain, joint pain, and headaches
  • Sore throat
  • Tender lymph nodes (glands) in the neck or armpits
  • Digestive issues, like irritable bowel syndrome
  • Chills and night sweats
  • Allergies and sensitivities to foods, odors, chemicals, light, or noise

ME/CFS can be unpredictable. Your symptoms may come and go. They may change over time; sometimes they might get better, and other times they may get worse.

ME/CFS can be difficult to diagnose. There is no specific test for ME/CFS, and other illnesses can cause similar symptoms. Your health care provider has to rule out other diseases before making a diagnosis of ME/CFS.

Your provider will do a thorough medical exam, which will include:

  • Asking about your medical history and your family's medical history.
  • Asking about your current illness, including your symptoms. Some questions they may ask could include how often you have symptoms, how bad they are, how long they have lasted, and how they affect your life.
  • Thorough physical and mental status exams.
  • Blood, urine, or other tests to check for other illnesses which could be causing your symptoms.

Your provider may also ask you to see a specialist to check for other conditions which can cause similar symptoms.

There is no cure or approved treatment for ME/CFS, but you may be able to treat or manage some of your symptoms.

You, your family, and your provider should work together to decide on a plan. You should figure out which symptom causes you the most problems and try to treat that first. For example, if sleep problems affect you the most, you might first try using good sleep habits. If those do not help, you may need to take medicines or see a sleep specialist.

Strategies such as learning new ways to manage activity can also be helpful. You need to make sure that you do not "push and crash." This can happen when you feel better, do too much, and then get worse again.

When you have ME/CFS, it can be hard to help develop a treatment plan. It can also be difficult to try to take care of yourself. So it's important that you have support from family members and friends.

There are also various resources and strategies that might be helpful to you, such as:

  • Getting counseling to help you cope with the illness and its impact on your life.
  • Eating a healthy diet.
  • Nutritional supplements, if your provider suggests them.
  • Complementary therapies such as meditation, gentle massage, or relaxation therapy.

Make sure to talk to your provider before you try any new treatments. Some treatments that are promoted as cures for ME/CFS are unproven, often costly, and could be dangerous.

Centers for Disease Control and Prevention

It sits within Bones, Joints and Muscles and Infections.

The lead U.S. institute for this subject is the National Institute of Neurological Disorders and Stroke.

When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.

Research on Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

217 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.

What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.

Research currently under way

Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.

Where to read more

Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.

Start Here

Symptoms

Diagnosis and Tests

Treatments and Therapies

Living With

Related Issues

Clinical Trials

Medical subject headings

Clinicians and researchers index this subject under Fatigue Syndrome, Chronic. These are the terms to use when searching medical literature.

This page is built from the MedlinePlus health topic record for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.