Canker sores are shallow, painful sores in the mouth. They are usually red or may sometimes have a white coating over them. You might get them on the inside of your lips, the insides of your cheeks, the base of your gums or under your tongue. Canker sores are different from fever blisters, which usually are on the outside of your lips or the corners of your mouth. Canker sores are also called aphthous ulcers.
Anyone can get canker sores, but women and people in their teens and 20s get them more often. Canker sores may run in families, but they aren't contagious. Doctors don't know exactly what causes canker sores. Mouth injuries, stress, poor nutrition, food allergies and menstrual periods are some of the things that may increase your chances of getting a canker sore.
There is no cure for canker sores, but they usually go away on their own in 7 to 10 days. For pain relief, you can try taking ibuprofen (two brand names: Advil, Motrin) or acetaminophen (one brand name: Tylenol). A number of over-the-counter medicines are available to relieve canker sore pain or to protect the sores from becoming irritated when you eat, drink or brush your teeth. Ask your doctor or pharmacist if one of these products might be right for you.
If your canker sores are large, last longer than 2 weeks, or are so sore that you can't eat or drink, you should make an appointment to see your doctor. He or she may prescribe a topical medicine (applied directly to the sore) or a special mouthwash to help.
You should also make an appointment with your doctor if you have a fever or feel sick when you have canker sores. Tell your doctor if you have canker sores more than 3 times a year.
You may be instructed to "swish and swallow" or "swish and spit" the medicine. This means that you swish the medicine around in your mouth, especially around your canker sore, for a few minutes before swallowing or spitting it out.
If you use a medicine that needs to be put directly on the canker sore, dry the sore with a cotton swab (like a Q-tip). Next, put a small amount of medicine on another cotton swab. Then, put the medicine on your canker sore using the swab. Don't eat or drink for 30 minutes. If you do, the medicine will be washed away.
Unfortunately, doctors don't know of anything that prevents canker sores from forming. However, you may be able to reduce mouth irritation by avoiding things like chewing gum, and hard, crunchy or spicy foods. Brushing your teeth with a soft toothbrush after meals and flossing every day will keep your mouth free of food that might trigger a canker sore. If you get canker sores often, or if they're very painful, talk to your family doctor.
Written by familydoctor.org editorial staff