Canker sores develop in the mouth as small white, yellow, or gray sores with a red border. There can be one sore or several. Just so you know, canker sores aren't contagious at all—so no need to take extra precautions if you're worried about spreading them. The most common sites for canker sores are inside the lips and cheeks, on the tongue, the base of the gums, and the mouth's roof.
Canker sores usually start with a burning or tingling feeling. They can also make talking or eating challenging. Minor sores typically heal after 1 to 3 weeks, while major ones may take up to 6 weeks. So be patient if you're healing with one right now. Also, heads up that sometimes another sore can appear after the first one heals.
If you're uncertain if you're experiencing a canker sore, check-in with your dentist. They'll be able to examine it and let you know right away.