Canker sore

Synonyms: Mouth sores, Aphthae, Recurrent oral ulcerations

Medical Specialties: Family practice, Pediatrics

Clinical Definition

Canker sores, also known as aphthous ulcers, are painful oral sores that are typically red in color but sometimes with a white, yellow or gray center. Traditionally less than a millimeter in diameter, they appear on the inside of the lips, inside the cheeks, under the tongue or at the base of the gums. Exact cause is not known.   

In Our Own Words

Canker sores are small, uncomfortable lesions that affect the lining of the mouth's soft tissue. They are often painful and can make eating and speaking difficult, but they are not contagious, pre-cancerous or sexually transmitted. Among the triggers are fatigue, emotional stress, mouth injuries, poor nutrition and PMS.

Teens and young adults get them more frequently than older adults. Individuals who are prone to canker sores may reduce their occurrence by using a soft bristle toothbrush, avoiding hot acidic foods (such as pizza sauce) and avoiding oral hygiene products with sodium lauryl sulfate. Healing usually occurs within a week to 10 days, and over-the-counter medications are widely available.  

Relevant Conditions
  • Hormonal changes
  • Vitamin deficiency
  • Weakened immune system
Common Types
  • Simple
  • Complex (recurrent)
Side Effects
  • Difficulty speaking
  • Accidentally biting the cheek or tongue
  • Pain and sensitivity in the mouth
Share this article
  • The Cleveland Clinic. "Canker Sores." Diseases & Conditions. Feb. 2011. Accessed Aug. 2013.
  • American Dental Association. "Canker sores and cold sores." Journal of the American Dental Association. March 2005. Accessed Aug. 2013.
  • American Academy of Family Physician. “Canker Sores." Diseases & Conditions. Sept. 2010. Accessed Aug. 2013.
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