Mouth ulcers, commonly referred to as canker sores, occur when the soft tissue in your mouth, known as mucous membrane, becomes damaged, most often on the inside cheek, and gums. No one knows exactly why this happens, but we do know that diet plays a part, as do genetics.
Canker sores are not contagious.
Once the skin is broken, it grows into an ulcer several times larger than the original wound. Canker sores can be small and barely noticeable, or can grow large with a white center. Sometimes a Canker sore can grow so large it will ultimately scar. Scar tissue may be less pliable and lead to further aggravation of the site and further canker sores.
Sources of irritation include anything which rubs or scratches the inner mouth tissues, as well as certain types of acidic foods. A common ingredient in most toothpaste, known as Sodium Lauryl Sulfate (SLS), can act to strip away protective layers within the mouth, and leave the mouth vulnerable to Canker Sores.
The first step most people should take to reduce canker sores is to buy a toothpaste which does not contain Sodium Lauryl Sulfate. Learn how you can reduce the number of canker sores you form by switching your toothpaste here.