A canker sore, or aphthous ulcers as they may also be regarded as, are little agonizing sores that form about the within of one's lips, cheeks, and in many cases on your tongue.
Never confuse a canker sore which has a fever blister or possibly a cold sore, that's a virus and varieties about the outside of the mouth in most all circumstances.
DISCLAIMER: DMOZing.com is not affiliated in any way, shape, or form with DMOZ, AOL, Netscape, their management, entities or their official websites. Links to external websites on this website does not constitute endorsement.