Canker sore
A canker sore is a common form of mouth ulcer, which appears as a painful white or yellow ulcer surrounded by a bright red area. A canker sore sore can be triggered by emotional stress, dietary deficiencies, menstrual periods, hormonal changes, food allergies or trauma in the mouth. Canker sores usually heal without treatment within two weeks.
Update Date: 5/13/2008 Updated by: Linda Vorvick, MD, Seattle Site Coordinator, Lecturer, Pathophysiology, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.