A canker sore is a shallow ulceration usually seen on the inner cheek or gums, but also seen on the tongue or throat.

The exact cause is not known, but may be a virus or other chemical, physical or microbial agent.  Canker sores may also be associated with prolonged fever, stress, infectious mononucleosis or inflammatory bowel disease.

These lesions are often painful.  Hot, irritating, or acidic foods, such as nuts, chocolates and citrus fruits, should be avoided.  Abstinence from these foods will not prevent recurrence, however.

A medication may be prescribed, such as medicated mouthwash.  If so, use as directed.

Other symptomatic treatment may include applying a wet tea bag directly on the sore (may give almost instantaneous relief); applying Zilactin® or Glyoxide® (over-the-counter preparations) to the sore; or gently rinsing the mouth with warm salt water (2 teaspoons salt in a large glass of water).  Stress reduction may help prevent recurrences.