Canker Sores

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Overview, Causes, & Risk Factors

Canker sores are a common form of mouth ulcer. They occur in women more often than men. They may occur at any age, but usually first appear between the ages of 10 and 40.

Canker sores usually appear on the inner surface of the cheeks and lips, tongue, soft palate, and the base of the gums.

They usually begin with a tingling or burning sensation, followed by a red spot or bump that ulcerates. Pain decreases in 7 to 10 days, with complete healing in 1 to 3 weeks. Particularly large ulcers (greater than 1 cm in diameter) often take longer to heal (2 to 4 weeks). Occasionally, a severe occurrence may be accompanied by nonspecific symptoms of illness, such as fever or malaise. Canker sores often come back again in the future.

There may be an inherited tendency to develop canker sores, as they often run in families. There may also be an immune system link. Ulcers may develop in response to a mouth injury such as dental procedures or aggressive tooth cleaning.

Canker sores may also occur at the site of a bite when the tongue or cheek is bitten. They can be triggered by emotional stress, dietary deficiencies (especially iron, folic acid, or vitamin B12), menstrual periods, hormonal changes, food allergies, and similar situations. They occur most commonly with viral infections. They may occur with no identifiable cause.