What are canker sores and what causes them?
Canker sores are shallow, painful sores on the inside of the lips, the inside of the cheeks, or on the gums. They begin as small, reddish swellings. Then they burst and the ruptured sores are covered with a white or yellow membrane. The edges of the sores are still red and look like a painful red halo. Without treatment, canker sores (medically: aphthous ulcers) heal in two to three weeks. Canker sores can run in families. They may also be linked to problems with the bodys immune defense system. Canker sores can be triggered by emotional stress, dietary deficiencies, menstrual periods and/or hormonal changes.
