What are canker sores?

What are canker sores?

Canker sores are small shallow ulcers that occur in the lining of the mouth. The medical term for canker sores is “aphthous ulcers.” Canker sores start as white to yellowish ulcers that are surrounded by redness. They're usually very small (less than 1 mm) but may enlarge to ½ to 1 inch in diameter. Canker sores can be painful and often make eating and talking uncomfortable. There are two types of canker sores:

• Simple canker sores: These may appear three or four times a year and last up to a week. Anyone can get canker sores but they typically occur in people between ages 10 and 20.
• Complex canker sores: These are less common and occur more often in the people who have previously had them.