"Cold sores are highly contagious by touch," explains Dr. Amy Forman Taub, a board-certified dermatologist who founded Advanced Dermatology in Lincolnshire, Illinois. "If you have one, don't kiss anyone. Also, wash your hands frequently and, if possible, cover [the cold sore] with a bandage." READ MORE to find out what Dr. Taub recommends is the number one way to avoid cold sores.