This is a painful ulcer you get in your mouth. It can
form inside your lip, on or under your tongue, on
your gum, on your cheek or on the roof of your
We don’t always know why canker sores form.
They may be linked to things like stress, hormones,
diet, injury, or sensitivity to food or toothpaste. They
may also be linked to certain conditions and
diseases. These sores don’t spread from person to
Canker sores are often white with a red border.
They can be small or large, and may be circular or
oval-shaped. Some have irregular borders. An
uncommon form, called “herpetiform” canker sores,
are the size of pinpoints. They may group in large
clusters in your mouth to form one large sore.
Most canker sores don’t need treatment. They heal
on their own after one to six weeks. A sore that’s
large or deep may leave a scar. You can help avoid
canker sores by managing stress, practicing good
oral hygiene, and by making sure braces or other
appliances don’t poke your mouth. Eat a healthy
diet, and avoid foods or drinks that irritate your
mouth. Talk to your dentist or doctor for more