herpes simplex
"Acyclovir 800 tab 4 times a day for 5 days. First pill stopped the cold sore in its tracks it immediately stopped growing with just the first pill. Second day the tingling phase stopped, they erupted, and by the end of the 2nd day they were drying out. I had to stop at the end of day 2 due to this medicine being too strong for my stomach. I ended up with a gastritis flare up, terrible stomach pain, diarrhea and nausea. If it wasn't for that, this medicine would get 10/10!"