| Canker sores (aphthous stomatitis) also known as mouth ulcers, are shallow, painful sores on the inside of the lips, tongue, the inside of the cheeks, or on the gums. Canker sores are most common among teenagers and people in their twenties. They begin as small, reddish swellings. Then they burst, and the ruptured sores are covered with a white or yellow membrane. The edges of the sores are still red, and look like a painful red halo. It is suspected that having too much acidity in your stomach, stress, and food allergies are major causes of canker sores. You may want to have allergy tests done or test yourself by eliminating the suspected foods from your diet for a few weeks, then reintroduce them one at a time and see which one triggers a canker. Canker sores differ from cold sores in that they occur in the soft tissues of your mouth and aren't contagious. Conversely, cold sores rarely develop in the soft tissues of your mouth and are extremely contagious because they're caused by the herpes virus. Without a canker sore remedy, canker sores can take from 1-3 weeks to heal. |