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