Most people have been bothered at one time or another by canker sores. Doctors call them aphthous ulcers, but the name doesn't explain the problem. In fact, physicians and dentists don't know what causes cankers, though many have tried to find out. Scientists have learned that they are not caused by herpes or any other known virus and that they are not contagious. And with rare exceptions, cankers are isolated problems that crop up in healthy people without indicating a serious medical condition.
Cankers are shallow ulcers that can develop on the inside of the cheek or lips or under the tongue. Most are pink or reddish, but some have a white coating. They are painful, so they make eating a chore, but they almost always clear up in about a week.
If you are one of the very few people who develop fever, swollen glands, weakness, eye or joint inflammation, abdominal cramps and diarrhea, or genital ulcers along with your cankers, you should see your physician. In the vast majority of cases, however, medical attention is not needed. You can simply wait it out: Avoid foods that trigger pain, and use a mild over-the-counter pain reliever if necessary. You can also make a soothing mouthwash by mixing equal parts of Milk of Magnesia and Benadryl Allergy liquid. Swish a teaspoon of the mixture in your mouth for 30–60 seconds, then spit it out. If it seems to help, you can repeat the rinse every four hours. For stronger relief, your physician or dentist can prescribe a local anesthetic such as benzocaine (Orabase-B) or lidocaine (Xylocaine Viscous). Use a Q-tip to paint the anesthetic on the sore 30 minutes before meals and as otherwise needed.
Although it's small comfort when your mouth hurts, keep in mind that up to half of all adults have experienced canker sores at least once.
February 2005 Update