Canker Sores

Canker Sores

Have you ever had a canker sore? If so, you know that these small mouth sores can cause major pain. You can get a canker sore on the inside of your lip or cheek, under your tongue or at the base of your gums. Usually canker sores form one at a time inside your mouth, but you can get more than one in a little cluster.

Canker sores are round and usually about the size of a kernel of corn (1/4 inch, or 6 millimeters), but they can be bigger. If you look in the mirror at your canker sore, it will be white or yellow with a red border.

aphthous ulcer illustration

What Do Canker Sores Feel Like?

Canker sores hurt, especially if you eat something hard, crunchy, salty, or acidic (like orange juice). They usually go away on their own and they are not contagious. So no one can catch a canker sore by kissing you or sharing your drink.

Other Kinds of Mouth Sores

Not all mouth sores are canker sores. Cold sores or fever blisters are a different kind of sore, which is caused by a virus called herpes simplex (say: hur-peez sim-pleks). Cold sores and fever blisters often form outside the mouth, around the lips, on the cheeks or chin, or inside the nostrils of the nose. Unlike canker sores, those sores are contagious. Chickenpox sores are another kind that are contagious, and it's possible to get chickenpox sores inside the mouth.

What Causes Canker Sores?

No one really knows what causes canker sores. But researchers think stress may make a person more likely to get one. A canker sore also may spring up if a person's diet doesn't contain enough vitamins and minerals.

The inside of your mouth is delicate, so mouth injuries, such as biting the inside of your lip or brushing your teeth too hard, also seem to bring on canker sores. But anybody can get a canker sore and they may run in families, which means that if your mom or dad gets canker sores, you might get them, too.

How Are They Treated?

Most canker sores don't hurt as much after the first few days, but it may take 2 weeks for the sore to heal. Here's a remedy for canker sores that you do not want to try.While you're waiting, you'll want to be careful when eating and brushing your teeth. Scraping the sore can make it hurt worse. You might need some medication to dull the pain. Your mom or dad can ask your doctor about which one is best for you.

If your canker sore is large, lasts longer than a week, or is keeping you from eating, you should see your doctor so he or she can check it out.

How Can You Prevent Canker Sores?

There's no guaranteed way to prevent canker sores, but it's a good idea to eat healthy, get enough sleep, and try not to get too worried or upset. Put canker sores on the list of things you don't have to worry about. They hurt for a little while, but before you know it, you'll be a sore loser!

Reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: January 2013





Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor.

© 1995-2014 The Nemours Foundation/KidsHealth. All rights reserved.





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Related Resources
OrganizationAmerican Dental Association (ADA) The ADA provides information for dental patients and consumers.
OrganizationAmerican Academy of Periodontology The American Academy of Periodontology provides information for consumers and dental patients about gum disease and oral health.
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