Typically, you notice a burning sensation and a round whitish spot with a red edge or halo.
Pain lessens in a few days.
Despite a great deal of research into the problem, the cause of canker sores remains a mystery. Current thinking suggests that stress or tissue injury may cause the eruption of common canker sores. A minor injury, such as biting the inside of your mouth, may trigger a canker sore. The first occurrence is usually between the ages of 10 and 20, but it can occur in younger children. As a person reaches adulthood, the sores occur less frequently and may stop developing altogether.