My girlfriend has canker sores. Can I catch them from her? – Matthew
No. Canker sores are not
. Unlike cold sores, you can't catch canker sores from another person.
So how can you tell if a sore is a (non-contagious) canker sore or a contagious cold sore? Cold sores usually develop outside the mouth, around the lips, chin, or nostrils. Canker sores are different: they only develop on the inside of the mouth.
Canker sores go away on their own after a while and usually don't need treatment. But if your girlfriend gets canker sores often, is in a lot of pain, or the sores don't improve within 2 weeks, she should see her doctor.