02/03/2016
What Are Cold Sores?
Cold sores -- also called fever blisters -- are a painful infection caused by the herpes simplex virus (HSV). These blisters are usually caused by HSV type 1, but can less commonly be due to HSV type 2. They may show up anywhere on your body, but are most likely to appear on the outside of your mouth and lips, your nose, cheeks, or fingers. Blisters form, then break and ooze; a yellow crust or a scab develops and eventually sloughs off, revealing new skinunderneath. The sores usually last 7 to 10 days and are contagious until they crust over completely.