I don't get cold sores very often and when not pregnant use Zovirax. I got the tingle the other day and went to the chemist and purchased the Compeed patches. This is the 3rd day I've been using them and I think I'll stop. Usually my cold sores don't end up very big and heal quickly but this one is the same size and shape of the patch.... it's disgusting. Could I actually be allergic to the patch for it to make the cold sore so big and ugly????