Introduction

Chronic fatigue syndrome is a frustrating and distressing illness that affects people of all ages. No one knows what causes it or why some people get it and others don't. There is no cure for the illness, but there are things you can try that may help you feel better.

We've brought together the best research about chronic fatigue syndrome and weighed up the evidence about how to treat it. You can use our information to talk to your doctor and decide which treatments are best for you.

Feeling tired is very common, especially if you have work or family problems or are under stress for other reasons. Many people say they feel tired most of the time, but very few of them really have chronic fatigue syndrome.

People with chronic fatigue syndrome (CFS for short) feel exhausted and weak a lot of the time for no obvious reason. Often they have other symptoms too. CFS can affect people of all ages.

There is no simple test for the condition, but your doctor may say you have CFS if you:^[1][2]

• Have been feeling exhausted for no known reason for more than six months

• Also have other signs of illness, such as muscle pains, sleep problems, headaches, and trouble concentrating or remembering things.

There has been a lot of research into CFS, but doctors still don't know what causes it. It could have several different causes.

What doctors do know now is that CFS is a real illness and not imagined, as was once thought.

Another name for the illness is myalgic encephalomyelitis (ME for short). Sometimes it is also known as CFS/ME. If your doctor finds signs that you have been infected with a virus, he or she may call your illness post-viral fatigue syndrome.

Sometimes CFS starts after another illness, like a bad cold or bronchitis. And some people find it starts during a time of stress. But it can come on gradually for no obvious reason.

Some people with CFS have abnormal levels of certain hormones. Doctors have also found they have changes in their immune system (the immune system helps the body fight infection). But no one knows whether these are causes or effects of the illness.

CFS doesn't go on for a set period of time. It can last from a few months to many years, although the symptoms may come and go during that time.

CFS can make you feel extremely unwell, and can disrupt your life. But many people find their condition can be improved with treatment.