You can easily tell if you have a mouth ulcer by its appearance. A mouth ulcer is:
- round or oval in shape
- white, red, yellow or grey in colour
- inflamed around the edge
Most mouth ulcers appear on:
- the inside of the lips
- the inside of the cheeks
- the floor of the mouth
- the under surface of the tongue
It's rare to get a mouth ulcer on the roof of your mouth.
Most mouth ulcers heal within 10 to 14 days, although they may last for several weeks in more severe cases.
When to see your GP
Visit your GP if you have a mouth ulcer that:
- gets progressively more painful and inflamed
- lasts for more than three weeks
Also visit your GP if you develop an ulcer somewhere else on your body, such as your genitals.
Read more about the diagnosis of mouth ulcer.
