Canker sores can affect anyone. However, they are most likely to affect women in their teens and 20s. The tendency to get canker soars may run in families. However, they aren't contagious. The exact cause of canker sores is unknown. However, doctors think that some of the causes could be stress, poor nutrition, food allergies or menstrual periods.
Canker sores usually go away on their own. Consulting a doctor is a good idea if the sores last more than two weeks, or are extremely sore, making it difficult to eat.