ARE MY LIPS just really chapped? Do I have cold sores ? These questions probably come to mind when you notice painful cracks in the corners of your mouth. But, more than likely, this dryness and crusting is an inflammatory skin condition called angular cheilitis, or AC. AC is commonly mistaken for cold sores . It can also resemble chapped lips , which is understandable, says Howard Rubin, M.D. , a board-certified dermatologist at U.S. Dermatology Partners North Dallas. "Although both are seen more frequently in the winter and colder, drier climates, angular cheilitis starts in the corners of the mouth and is usually bilateral," he explains. "AC may lead to fissures or cracks in the affected areas. Severely chapped lips are more often noted on the body of the lip." AC is relatively common. Dr. Rubin says it's associated with excess saliva pooling in the corners of your mouth. When the skin on your lips, which is already thin and sensitive, comes in continuous