Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Canker sores occur in several forms. They can involve any area of the mouth except for the top of the tongue, lips, and hard palate.
Minor canker sores (which account for the majority of aphthous ulcers) are oval and less than 10 mm (1/3 inch) across. Most are 2-3 mm with a white center. They are painful but clear up within three to 14 days without scarring. It is unusual for them to become infected.
Major canker sores consist of deep ulcers measuring greater than 1 cm (1/3 inch). These ulcers, which are very painful, have irregular margins and often last for three to six weeks. They tend to heal with extensive scarring.
A third form of canker sores, termed "herpetiform," resemble herpes infections and consist of many small shallow punched-out lesions, pinhead-sized (1-3 mm) in diameter, or less than 1/10 of an inch. Clusters of these sores may merge together to form large irregular ulcers. They last from seven to 10 days.
Canker sores commonly come back. Some people have a few outbreaks a year, while others can have them almost all the time.
When to Seek Medical Care
You should seek medical attention if any of the following occur:
It is your first episode and you are not sure about the diagnosis.