The NHS says that mouth ulcers are common, and most of them are harmless. But sometimes, they say, ulcers ― small, usually circular sores that form on the inside of your lip, inner cheek ...

Common mouth ulcers, known as aphthous ulcers or canker sores, can bother us all. They’re normally only about 2-3mm in size but can be surprisingly painful. They occur when a patch of the ...