Herpes Simplex
"got my first cold sore in 2010. started first with a tingle, then itchy, then inflammation as the blister tried to make it to the surface.  There was a raised, circular shape where I knew the cold sore was coming. Rushed to Walmart to get abreva (back then it was still in the tube and $16) and applied it about every 2-3 hrs that day. The blister itself never actually was able to form into an unsightly sore (no scab), though I still saw the circular, raised area which took about 3-4 days to fully disappear.  Over the course of a year, I had about 3 more cold sores in the same spot, always applied abreva at the first tingle and it never surfaced.  This week got a cold sore for the first time in 7 years, put on abreva and again, never surfaced"