herpes simplex, suppression
"I have had a cold sore outbreak 1-2 x/year for last 15 years usually during summer months (lower lip).  I had previously tried medicated lip applicators with little success. A friend suggested Zovirax.  I use it now at the first sign of tingling or hardness in the lip.  When I catch it early the severity of the outbreak has been greatly diminished.  I only use for 2 days and the sore has usually healed in about 10 days to 2 weeks."