I started a new thread as it was over a year since the subject was raised here. I saw in 2016 a lot of you were using Zovirax and Aciclovir. My limited experience with the former - it doesn't do much. In attempts (successful) to treat other skin issues I had been having I discovered that Hydrogen Peroxide 6% solution diluted in water had a great effect on my new coldsore. Applied with a small piece of cotton wool initial and then a cotton bud - apply 3 times a day until a scab is formed. For me the first stage only took 24 hrs. Resolution will depend on your own healing powers but getting this blister to dry up and scab means it is no longer infectious. I tend to be able to get rid of a scab in 2 to 3 days. Cheaper than Zovirax and more effective (have not used Aciclovir for coldsores but side effects don't look good.