A small, painful sore or ulcer that occurs inside the mouth. It is usually surrounded by an area of redness less than 2 inches in diameter. Canker sores commonly first appear when a person is in his or her 20s or 30s. The sores tend to disappear in 1 to 2 weeks. Recurrences are common and may be induced by trauma, eating spicy or citrus foods, and menstruation.
Tiny ulcers found on the inside of the mouth, often lacking a known cause, although some may result from food allergies. The numerous recommended treatments for this condition suggest a lack of precise understanding regarding its origin. These small ulcers can be treated by applying either pure carbolic acid or a solution of chromic acid, which encourages them to heal. They are also known as aphthous ulcers.