What Are the Symptoms?

The main symptom of a canker sore is getting a shallow ulcer on your tongue or on the inside of your lip or cheek. The sore may be large or small, and it will have a red border and a white or yellow center. You might have more than one canker sore at a time.

Canker sores usually begin with a burning or tingling feeling. They may be swollen and painful. Having a canker sore can make it hard to talk or eat.

Canker sores may hurt for 7 to 10 days. Minor canker sores heal completely in 1 to 3 weeks, but major canker sores can take up to 6 weeks to heal. Some people get another canker sore after the first sore has healed. Most canker sores heal without a scar.