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Canker sore

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Canker sore

Lip pulled back to show canker sore on inside of lower lip.

A canker sore is a painful white ulcer in the mouth. They appear most often on the tongue, inside of the cheeks, and inside of the lips. Unlike cold sores, canker sores are not contagious. But in some people they keep coming back. Canker sores cause pain that may make it difficult to eat or drink.

Current as of: August 6, 2023

Author: Healthwise Staff
Clinical Review Board
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