Mouth ulcer

Mouth ulcers are painful, clearly defined, round or oval sores that form in the mouth. They are sometimes also known as aphthous ulcers.

Types of mouth ulcer

There are three main types of mouth ulcer:

• Minor ulcers are the most common type, accounting for 80% of all cases. They are small (2-8mm in diameter) and usually heal naturally, within 10-14 days. A minor ulcer will not cause any scarring.
• Major ulcers are deeper and larger than minor ulcers, and usually have a raised or irregular border. They are usually 1cm or more in diameter. Major ulcers take longer to heal (several weeks) and can cause scarring.
• Herpetiform ulcers form as multiple, pinhead-sized sores. The number of ulcers can range from five to 100. These tiny ulcers often fuse together to form larger, irregular shaped sores, which are very painful. Around 5-10% of mouth ulcers are herpetiform. Herpetiform ulcers are not related to the herpes virus.

How common are mouth ulcers?

Mouth ulcers are very common. Most people will have at least one during their lifetime. They affect at least 20% of the population. Studies have shown that mouth ulcers are more common in women.

Mouth ulcers are more common in young adults.

Mouth ulcers cannot be passed from person to person. For example, you cannot get an ulcer from kissing someone or from sharing drinking glasses or cutlery.

Recurrent mouth ulcers

Most people only have mouth ulcers occasionally. However, some people develop mouth ulcers on a recurring or frequent basis. In the UK, one person in five will have recurrent mouth ulcers. About 5-10% of children can have recurrent mouth ulcers.

The factors that cause recurrent mouth ulcers are often different from those that cause single ulcers. See the Mouth ulcer - causes for more information.