Mouth ulcers are also known as aphthous ulcers or canker sores. They are sores which are found in the lining of the mouth (often on the moveable parts of the mouth). They are usually very painful, and, unfortunately, a person can have several of them at once. They are grey to white in colour.

It is not yet fully understood what causes mouth ulcers. They do not appear to be caused by bacteria or viruses and are not infectious or contagious. Genetic studies have shown that a susceptibility to them can be inherited, therefore family members sometimes share the condition.

Women are also more likely than men to have recurrent ulcers. However, for women who do get them, they often only occur during certain phases of their menstrual cycle. Some women also experience an improvement during pregnancy. For these reasons, it is thought that female sex hormones play a role in causing mouth ulcers.

In some people they occur because of an allergic reaction to certain foods. There is some research that suggests they may occur due to a faulty immune system. In this case, the body's immune system, which is normally used to fight disease, attacks the normal cells of the mouth or tongue. There also seems to be some link between being run down and getting ulcers.

If the ulcers are being caused by another illness you have, then treatment of that illness may get rid of the ulcers.

Rinsing with antiseptic mouthwash or warm salt water may ease the pain. Similarly, take care not to eat anything with sharp edges, such as crisps, as they may scrape against the ulcers causing discomfort and pain.

Visit your doctor or dentist for advice.

Mouth ulcers may take up to two weeks to fully disappear. The most painful phase usually ends after three or four days. They will usually just go away on their own. Unfortunately there is no known way of stopping them from recurring.