cold sores
"I recently started taking valtrex again for prevention/treatment of genital herpes flare ups and every time I take one I get a cold sore on my mouth. Didn't take valtrex for a few years and never had a cold sore, I had other outbreaks but no cold sores. I got back on valtrex to control the other outbreaks about three months ago and cold sores have been a constant threat."