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.