What causes canker sores and what can you do about them?

Canker sores are extremely common, often painful, and rarely associated with serious disease, according to the National Institute of Dental and Craniofacial Research, part of the National Institutes of Health.

Technically called “aphthous stomatitis,” canker sores are little ulcers that occur inside the mouth on movable structures such as the tongue and lining of the cheeks and lips.