Canker Sore Causes What causes a canker sore? The cause of
canker sores is unknown, but they tend to run in families.
Canker sores may also develop when you: - Are stressed or tired.
- Have your menstrual cycle, if you are a woman. - Hurt your
mouth, such as biting your lip. - Have braces on your teeth. -
Have food allergies. Eating foods that you are allergic to may
cause you to get a canker sore. - Eat or drink food or juice
that has a lot of acid, such as orange juice. - Do not get
enough vitamins or minerals in your diet, such as iron.