A canker sore, also known as an aphthous ulcer, is a small, shallow ulcer that develops on the soft tissues in your mouth or at the base of your gums. They are not contagious and can’t be spread through saliva. Canker sores usually have a white or yellow center and a red border, and they can be extremely painful. They can occur singly or in clusters on the inside surfaces of your cheeks or lips, on or under your tongue, at the base of your gums, or on your soft palate.

The exact cause of canker sores is unknown, but they can be triggered by a number of things, such as stress, tissue injury, certain foods, hormonal shifts during menstrual cycle, a diet lacking in vitamin B-12, zinc, folic acid, or iron, genetics, sensitivity to certain foods, toothpaste containing sodium lauryl sulfate, and certain medical conditions.

Canker sores usually go away within two weeks, even without treatment. However, if you have unusually large canker sores, recurring sores, persistent sores lasting two weeks or more, sores that extend into the lips themselves, pain that you cant control with self-care measures, extreme difficulty eating or drinking, or high fever along with canker sores, you should see your dentist or healthcare provider.

To reduce the risk of canker sores, you can try stress reduction techniques, avoid foods that trigger them, use a soft brush to help prevent irritation to delicate mouth tissues, avoid toothpastes and mouth rinses that contain sodium lauryl sulfate, and protect your mouth if you have braces or other dental appliances.

Self-care measures to ease the pain of canker sores include using over-the-counter or prescription gels, ointments, and rinses, rinsing your mouth with salt water or mild, over-the-counter mouthwashes, applying a mixture of half hydrogen peroxide and half water directly to the sore using a cotton ...