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Symptoms
By Mayo Clinic staff
Most canker sores are round or oval with a white or yellow center and a red border. They form inside your mouth — on or under your tongue (soft palate), inside your cheeks or lips, and at the base of your gums. You might notice a tingling or burning sensation a day or two before the sores actually appear.
There are several types of canker sores:
- Minor canker sores. The most common type of canker sore is an oval lesion, less than 1/3-inch (7.62 millimeters) wide that clears on its own in about two weeks. Though not serious, minor canker sores can be very painful.
- Major canker sores. These are large lesions with irregular margins that can last months or even years. They often heal with extensive scarring.
- Herpetiform canker sores. These are clusters of dozens of tiny lesions that may merge to form a single large ulcer. Herpetiform canker sores usually develop later in life and may last from a week to a month or more.
Occasionally, you may experience other signs or symptoms along with the lesions, such as:
- Fever
- Listlessness
- Swollen lymph nodes
