@fify-- I think that's just a stage the blister goes through. There are numerous stages of a herpes blister. First, skin tingles and itches. This is a sign that a blister is getting ready to emerge. A red bump develops and a few days later, it becomes an ulcer. So a virus and white blood cell filled pus forms in the center. Several days later, the ulcer pops and leaks this fluid. Then the blister dries up and eventually goes away.
It is possible to shorten the duration of a blister or get rid of it before it turns into an ulcer. If certain precaution are taken as soon as the tingling begins or as soon as the red bump appears, the other stages can be skipped. Taking lysine supplements or using lysine creams, using an anti-viral medication or certain home remedies can prevent blisters or cause them to heal quickly.
I was able to get rid of a cold sore in just a few days (and without ulceration) with the use of salt. I basically applied salt to the ulcer several times a day. It burned a lot however and it was painful, so you may want to use an over-the-counter cold sore cream instead.