Herpes simplex type 1, the virus that causes oral herpes, is very contagious. In fact, approximately 90% people in the U.S. will have antibodies (showing exposure) to HSV-1 by the age of 40. It's difficult to avoid infection. In order to prevent catching the virus, do not kiss or share personal items (eating utensils, cups, lipstick, lip balm, razors, etc.) with anyone who has a cold sore -- but bear in mind that a cold sore doesn't have to be present for a person to have and spread the disease.
