What causes canker sores?

The exact cause of canker sores is not known. Some factors may include genetics, allergies, stress, and vitamin and mineral deficiencies. Trauma to the inside of the mouth can result in the development of canker sores. Ill-fitting dentures or braces, toothbrush trauma from brushing too hard, or biting your cheek, may produce canker sores.

Certain foods may also be a factor. Citrus or acidic fruits and vegetables can trigger a canker sore or make the problem worse. Foods like chips, pretzels and hard candies have sharp edges that can nick and injure the soft tissue of the mouth.

To treat a canker sore, rinse your mouth with antimicrobial mouthwash or warm water and salt. Over the counter treatments are also available.

If the canker sore is present longer than two weeks, see your dentist.