Canker Sores Directory

Canker sores are small, painful ulcers in the mouth. There are two types: primary and complex. Canker sores may be caused by stress, injury, irritating foods, nutritional problems, and an impaired immune system, among other things. Most heal without treatment, but extremely painful ones may warrant a prescription treatment. Follow the links below to find WebMD's comprehensive coverage about how canker sores are contracted, what they look like, how to treat them, and much more.

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