"Herpes labialis, (also called cold sores, herpes simplex labialis, recurrent herpes labialis, or orolabial herpes), is a type of herpes simplex occurring on the lip, i.e. an infection caused by herpes simplex virus (HSV). An outbreak typically causes small blisters or sores on or around the mouth commonly known as cold sores or fever blisters. The sores typically heal within 2–3 weeks, but the herpes virus remains dormant in the facial nerves, following orofacial infection, periodically reactivating (in symptomatic people) to create sores in the same area of the mouth or face at the site of the original infection.
Cold sore has a rate of frequency that varies from rare episodes to 12 or more recurrences per year. People with the condition typically experience one to three attacks annually. The frequency and severity of outbreaks generally decreases over time."