What does a canker sore look like?

Canker sores appear inside the mouth. They usually are small ulcers (minor aphthous ulcers) with a white, yellow or gray center and a flat red border. Rarely, canker sores can be very large (major aphthous ulcers) with a raised border. There may be one or several ulcers and they recur at varying periods of time.

A canker sore usually begins as a red spot or bump. It may produce a tingling or burning sensation before other symptoms appear. Canker sores are painful. Fortunately, most canker sores heal spontaneously in 7 to 10 days.

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Canker Sores

Canker Sores

Aphthous stomatitis is a sore that forms inside the mouth, and the most common type is a canker sore. These sores, also called mouth ulcers, are yellow-gray with red rings around them and usually heal in a week or two. Sometimes c...

anker sores are larger or occur in clusters and can take over a month to heal. Treatment is usually with an oral antiseptic and analgesic. Learn more about what affects your risk for canker sores with expert advice from Sharecare.
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