Zovirax Cold Sore Cream Pump by GSK. Zovirax Cold Sore Cream is an effective treatment for cold sores. It contains the antiviral agent aciclovir and the patented MAC-P carrier, which helps to carry aciclovir to the site of the cold sore. This means, by using Zovirax, you can cut the healing time for your cold sore by up to half (compared to no treatment). The active ingredient aciclovir by itself is poorly absorbed. Zovirax has patented MAC-P to assist aciclovir to penetrate the skin and reach the site of the infection. There are 4 stages of a cold sore – tingle, blister, weeping and scab. You can use scientifically proven Zovirax Cold Sore Cream at any stage to speed healing and get rid of your cold sore fast.