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: March 25, 2020
Author: Healthwise Staff Medical Review: Kathleen Romito, MD - Family Medicine Martin J. Gabica, MD - Family Medicine Adam Husney, MD - Family Medicine Arden G. Christen, DDS, MSD, MA, FACD - Dentistry