Abreva (docosanol) is an antiviral topical medication used to shorten the healing time of cold sore/sun blisters caused by the herpes simplex virus reactivation, which remains inactive in the dorsal root of your spinal ganglia and gets activated under certain conditions. Cold sores affect 15-30% of the US population and its usually triggered by sun exposure, emotional stress, menstruation, skin trauma, and fever. It should be applied up to five times a day until healed usually from 7-10 days. If you miss a dose apply the missed dose and re-apply the next dose scheduled. During, before, and after outbreaks or if blisters are present cold sores are contagious so you should avoid close physical contact, to avoid spreading the infection and never share docosanol with anyone.