Mouth ulcers are painful, clearly defined, round or oval sores that form in the mouth.

There are three main types of mouth ulcer, which are outlined below:

Minor ulcers are the most common type of ulcer. They are small (2-8mm in diameter) and usually heal naturally within 10-14 days.

Major ulcers are larger and deeper than minor ulcers, and usually have a raised or irregular border. A major ulcer is usually 1cm or more in diameter. This type of ulcer will heal more slowly, over a period of several weeks.

Herpetiform ulcers form as multiple, pinhead-sized sores. The number of ulcers can range from 5 to 100. These tiny ulcers often fuse together to form larger, irregular shaped sores, which are extremely painful.

A mouth ulcer is a very common condition, and most people will have at least one in their lifetime.