The most common type of mouth ulcers are “aphthous ulcers”. These  painful mouth ulcers can affect about 20 -30% of the population, tending to start in childhood and getting less frequent as a person gets older. Aphthous ulcers are usually small, with a white, grey or yellowish colour in the middle, and a red edge. The pain is increased by eating spicy or acidic foods. Some people get larger, deeper mouth ulcers and others may get multiple mouth ulcers at the same time. However, there are other causes of mouth ulcers – including infections, inflammatory conditions, oral cancer and illnesses or medications that weaken the immune system.

If mouth ulcers are severe, very frequent or worsening over time, it is important to see a doctor or dentist for assessment.

In this section we look at aphthous ulcers and other causes of mouth ulcers, as well as the relevant investigations and treatment options.