Canker sores (mouth ulcers) are ulcers that occur within the mouth. Since canker sores are incredibly painful, it’s natural that you would want to do everything in your power to avoid them. Of course, avoiding canker sores first begins with being able to identify them as well as understanding their most common causes.

Canker sores look like small white or reddish holes on the inside of the lips, under the tongue or along the gum line. They typically start out pink or reddish in color and then, as they progress, turn white. So, just what causes these pesky sores, anyway? The first cause on our list affects more than 50 million people in the United States each year…