Written By Kassandra Foreman / Reviewed By Ray Spotts
A canker sore is within the mouth or on the lips and appears as a round spot with a yellow or red interior and a red circle around it. These will generally go away on their own if left untreated, but can occasionally last longer than a few days and can then be treated to decrease discomfort. While mostly harmless and safe to ignore they can occasionally cause larger concerns and may even lead to tooth damage.
