Chronic fatigue syndrome - What is it?

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.

Doctors don't know what causes 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 signs of illness too. There is no simple test for the condition, but your doctor might 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 chronic fatigue syndrome 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 might call your illness post-viral fatigue syndrome.

Sometimes chronic fatigue syndrome 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.

Chronic fatigue syndrome 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.

References

Fukuda K, Strauss S, Hickie I, et al. The chronic fatigue syndrome: a comprehensive approach to its definition and study. Annals of Internal Medicine. 1994; 121: 953-959.
Sharpe M, Archard LC, Banatvala JE. A report: chronic fatigue syndrome: guidelines for research. Journal of the Royal Society of Medicine. 1991; 84: 118-121.

Glossary

infection: You get an infection when an , such as a or , gets into a part of your body where it shouldn't be. These organisms are so tiny that you can't see them without a microscope. An infection in your nose and airways causes the common cold. An infection in your skin can cause rashes such as athlete's foot.
viruses: Viruses are microbes that need the cells of humans or other animals to exist. They use the machinery of cells to reproduce. Then they spread to other cells in the body.
bronchitis: Bronchitis is inflammation of one or both of the major airways (also called bronchi) that lead in and out of the lungs.
hormones: Hormones are chemicals that are made in certain parts of the body. They travel through the bloodstream and have an effect on other parts of the body. For example, the female sex hormone is made in a woman's ovaries. Oestrogen has many different effects on a woman's body. For example, it makes the breasts grow at puberty and helps control periods. It is also needed to get pregnant.
immune system: The immune system is made up of the parts of the body that fight infection. The body is constantly being threatened by infections from things like bacteria, viruses and parasites. The immune system fights these infections in different ways. At the microscopic level, the immune system uses antibodies and white blood cells, which travel in the blood and target infectious agents, such as bacteria. These microscopic parts of the immune system either kill the infectious agent directly, or take it to other parts of the body, like the spleen, where it can be dealt with. The lymph nodes are another important part of the immune system. Within them, white blood cells filter through the foreign material that has entered the blood, to see if there are any infections. When you have a swollen gland during a cold, this is actually a lymph node that is reacting to the infection. Unfortunately, it is possible for the immune system to become confused and to attack healthy parts of the body. Diseases that result from this type of situation are called autoimmune diseases.

This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.