Indication for the topical treatment of recurrent oral-facial herpes simplex episodes (cold sores or fever blisters).pharmacodynamics docosanol is a saturated 22-carbon aliphatic alcohol which exhibits antiviral activity against many lipid enveloped viruses including herpes simplex virus (hsv). docosanol speeds the healing of cold sores and fever blisters on the face or lips. it also relieves the accompanying symptoms, including tingling, pain, burning, and itching. docosanol cannot, however, prevent cold sores or fever blisters from appearing.mechanism of action docosanol works by inhibiting fusion between the human cell plasma membrane and the herpes simplex virus (hsv) envelope, thereby preventing viral entry into cells and subsequent viral replication. unlike other cold-sore antivirals, docosanol does not act directly on the virus, and as such it is unlikely it will produce drug resistant mutants of hsv.