Canker sores, also called aphthous ulcers, are small, shallow lesions that develop on the soft tissues in your mouth or at the base of your gums. Unlike cold sores, canker sores don’t occur on the surface of your lips and they aren’t contagious. They can be painful, however, and can make eating and talking difficult.
Most canker sores go away on their own in a week or two. Check with your doctor or dentist if you have unusually large or painful canker sores or canker sores that don’t seem to heal.
Symptoms
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, inside your cheeks or lips, at the base of your gums, or on your soft palate. You might notice a tingling or burning sensation a day or two before the sores actually appear.
There are several types of canker sores, including minor, major and herpetiform sores.
Minor canker sores
Minor canker sores are the most common and:
Are usually small
Are oval shaped with a red edge
Heal without scarring in one to two weeks
Major canker sores
Major canker sores are less common and:
Are larger and deeper than minor canker sores
Are usually round with defined borders, but may have irregular edges when very large
Can be extremely painful
May take up to six weeks to heal and can leave extensive scarring
Herpetiform canker sores
Herpetiform canker sores are uncommon and usually develop later in life, but they’re not caused by herpes virus infection. These canker sores:
Are pinpoint size
Often occur in clusters of 10 to 100 sores, but may merge into one large ulcer
Have irregular edges
Heal without scarring in one to two weeks
When to see a doctor
Consult your doctor if you experience:
Unusually large canker sores
Recurring sores, with new ones developing before old ones heal, or frequent outbreaks
Persistent sores, lasting two weeks or more
Sores that extend into the lips themselves (vermilion border)
Pain that you can’t control with self-care measures
Extreme difficulty eating or drinking
High fever along with canker sores
