What Are Cold Sores?

Cold sores are small, painful, fluid-filled blisters or sores that appear on the lips, mount or nose. Several of these small blisters may cluster to form one large blister, which may ooze before crusting over. They are caused by the herpes simplex virus (HSV) and usually last a few days.

The virus is spread from person to person by kissing or other close contact with apparently normal skin that is shedding the virus. Some people have a ‘prodrome’, — an early symptom warning before the actual sores appear — typically a burning or tingling sensation a few hours or a day or two before.