You Wanted to Know: Canker Sores


If you’ve ever had a painful, round ulcer on the inside of your mouth or gums, you may have been struck by a canker sore, otherwise known as an aphthous ulcer. One of our viewers, Ginger, asked me about what can cause these uncomfortable lesions:


Unlike cold sores, which tend to appear on or near the lips and are caused by the herpes virus, canker sores are not caused by a virus and are not contagious. The cause of these painful ulcers is not definitively known, but they are thought to be related to a malfunction of the immune system.

A common trigger for canker sores is injury to the inside of the mouth, as can occur from dental work, spicy foods, overzealous brushing or biting your tongue or cheek. As Ginger suggests, emotional stress can also contribute to their formation, along with hormonal changes, food allergies and a deficiency of certain vitamins and minerals such as iron, folic acid or vitamin B-12. More rarely, canker sores may accompany serious diseases, including celiac disease, inflammatory bowel disease, Behcet’s disease and HIV/AIDS. Women are more likely than men to get them and a family history of them may up your risk, but they can pop up in anyone and are very common.

The first sign of a canker sore might be burning or tingling over the site where it’s going to appear. Then, one or more sensitive bumps or spots develops into an open ulcer, usually with a white or yellow center and a red or gray ring around it. They usually stay relatively small (under 1/3 of an inch) and heal on their own. Pain usually lasts around 7-10 days, but it can take several weeks for the ulcer to completely resolve (longer if it is a particularly large or deep sore).

If you have a canker sore, avoid hot or spicy foods, which can make symptoms worse. Maintain good dental hygiene with regular brushing, but be gentle. You can also look for toothpaste and mouthwash that is free of sodium lauryl sulfate, a chemical that can cause or worsen canker sores in some people. Rinse your mouth frequently with warm salt water to help reduce inflammation and cleanse the ulcer. Certain over the counter medications like benzocaine gel can help ease discomfort and provide a protective barrier that will help the ulcer heal. A tea bag dipped in room-temperature water may also help soothe the ulcer if held against it for five minutes, several times a day.

If you have unusually large or deep canker sores, recurring sores that develop before your old ones have healed, persistent sores that last three or more weeks, sores that erode into your lip, extreme pain, high fever or severe trouble eating or drinking, see your doctor or dentist. Ulcers in the mouth that do not heal can be a sign of oral cancer, so pay special attention to make sure your ulcers resolve and seek medical attention promptly if they do not.