herpes simplex
"I skipped the tingle stage all together. My lips had been really dry and I was using Chapstick when all of a sudden there was a random blister on my lip. I immediately went and bought some Abreva. It never got past the blister stage. It has been 2 days and it just looks like a dry patch now. No scab. No oozing. Can't even tell it's there if you didn't know."