herpes simplex
"This is the only thing that works for myself stress induced break outs (college). I use both the pills and the cream. I believe when I first started using acyclovir it was more effective  and now it can take a good 4-5 days to fully heal. This is nothing in comparison to a cold sore that lasted a month without the meds though! 400mg. Free with my healthcare for the pills, the cream was $25."