Not many people are fond of this remedy, but I personally use salt to treat a cold sore in the nose or on the lips. Yes, it burns and irritates a little bit but it dries out the cold sore and reduces its lifespan.
I wash my hands and while my fingers are still wet, I take some salt, rub it slightly and apply it directly on the cold sore. It burns a lot but I keep it on for at least fifteen seconds so that the salt kills the virus. I repeat this several times a day for several days. Salt stops the cold sore and turns it into a dry scab after several days. Healing time goes down by almost half. But it's important to use some vitamin E oil afterward to prevent scarring from the scab though.