Herpes labialis

Herpes labialis, also called cold sores among other names, 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. The sores typically heal within 2–3 weeks, but the herpes virus remains dormant in the facial nerve branches, 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.