Thanks to a tip from one of our valued readers Helen, Healthy Hints has discovered that one of the best cures for cold sores is Aloe vera gel. As a remedy it is soothing, antiviral, antibacterial and inexpensive. Fresh is best, and growing this useful and hardy plant is incredibly easy - but in case of emergencies you can purchase Aloe vera gel from a chemist or health shop.
I believe putting an ice block on the sore area of the lip, as it just starts to get itchy, swollen or sore is very efficacious. Keep it on for as long as you can stand it - It seems to kill the bugs that are invading that area.
Also, a friend said her parents use to iron a hanky and place this on the sore area. If you can get to a chemist Zovirax seems to be the definite fix.
Basically a low immune system is why you get them (and most of us have the 'herpes simplex' bug in us waiting to pop out when our immune systems are very low). Eat well, keep warm and sleep!