I get cold sores on a regular basis. Horrible big ones just under my right nostril , they last ages and look like I've got a massive bogey .
The last time I felt the awful telltale tingling , I slapped a thick layer of Dermavate on it because it was the only 'medical' cream I had to hand and Zovirax has never helped anyway. It didn't stop it forming but I didn't get the blisters and it went within 3 days.
I felt one coming yesterday , slapped on the Dermavate and today it's just flat and red , no blisters , no crusting.