What are canker sores?

Canker sores and acidic foodsCanker sores are small, shallow holes or breaks in the skin that are located in the mouth. Simple canker sores are thought to be triggered by stress or tissue injury from sharp food or objects in the mouth. Some foods that are acidic such as fruits and vegetables may also cause or worsen a canker sore.

A more complex canker sore are suspect as a sign to a larger health problem such as a gastrointestinal issue or nutritional problems or deficiency.

Unlike a cold sore, canker sores are not caused by a virus, not contagious, and are found inside the mouth, not outside like a typical cold sore.


Canker sores can usually heal within their own time in a week or two, but if painful, can be treated by your dentist. If you find that you frequently suffer from canker sores, you may try avoiding acidic or spicy foods or try changing to a soft-bristled toothbrush.

If you are seeing larger, unusual sores, sores that are spreading or not going away after 3 weeks, or high fever with the appearance of canker sores, you should contact your dentist.