Aphthous ulcers are also known as canker sores. They are painful, temporary sores that may occur anywhere in the mouth. The sores can occur one at a time or as a group. Although canker sores are not serious, other mouth sores may be. If you suspect you have this condition, make an appointment to see your doctor.

Canker Sores in the Mouth
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No one knows exactly what causes canker sores. They are thought to result from an overreaction of the immune system.

Canker sores are not a form of the herpes virus. Unlike herpes, canker sores cannot spread from one person to another.