Usually a single mouth ulcer is due to damage caused by biting the cheek or tongue, or by sharp teeth, brushing or poorly fitting dentures. These ulcers are called ‘traumatic’ ulcers. If you have a number of mouth ulcers, and they keep coming back, this is called ‘recurrent aphthous stomatitis’.
Recurrent aphthous stomatitis is a common problem, and is the repeated appearance of mouth ulcers in otherwise healthy children and young people. The cause is not known, but it is not infectious and is unlikely to be inherited.
Minor ulcers are the most common. They can appear inside the cheeks, and on the lips, tongue and gums and, more rarely, on the roof of the mouth. Most of these ulcers are the size of the top of a pencil and can sometimes come in clusters. You can get four to six at any one time.
Large ulcers are more severe and can take longer to heal. Any ulcer that lasts longer than 3 weeks should be checked by your dentist. Large ulcers may appear near the tonsils and can be very painful, especially when you swallow. You usually only get one at a time.
It is also possible to have up to 100 very small, painful ulcers which last for one to two weeks. However, these last two varieties are very rare.
You may get ulcers in other parts of the body such as your eyes or genital area. It is important to tell your dental team about this.
Cancer of the mouth can first appear as a mouth ulcer. The ulcers caused by mouth cancer are usually single and last a long time without any obvious nearby cause (for example a sharp tooth). Any ulcer that lasts longer than three weeks should be looked at by your dentist. Ulcers caused by cancer usually appear on or under the tongue, but may occasionally appear somewhere else in the mouth. Cancer of the mouth is usually linked to heavy smoking and drinking. Doing both together greatly increases the risk.
If an ulcer lasts more than 3 weeks you should always ask the dental team or doctor for advice. They may be able to tell you the cause and provide treatment, or they may arrange more tests or refer you to a specialist if needed.
Most ulcers heal up on their own. However, if they don’t heal within three weeks you should visit your dentist. Your dental team will be able to examine your mouth to check that the problem is an ulcer and not something more serious such as mouth cancer. If you suffer from ulcers that come and go often, you should visit your dental team to check that there is not an underlying medical cause.