A friend uses some type of lip balm containing lysine.
Since I have a heavy metal problem and since cadmium and mercury compete with zinc (they are in the same column of the periodic table), zinc is something to consider.
I particularly like the highly potent zinc acetate lozenge from Life Extension. I typically don't even need more than a quarter of the large lozenge.
On occasion I've just chewed a quarter tablet of 50mg Zn gluconate from the local pharmacy and then made sure the paste from my saliva coated the cold sore. It doesn't taste terrible but not as pleasant as the lef.org product.
Results have been remarkable for me; however that might be due to my HM problem.
I cant say I've ever heard that this worked for others.