My baby sister takes it when she feels a cold sore threatening, and it seems to lessen their staying power and horridness. I'll take it when I'm feeling a lot under the weather - usually because I've not been sleeping properly for a while - or when I'm off at a festival or in some similar not-eating-properly, not-sleeping-properly environment. It does appear to help to ward off bugs then. I have no idea if it actually does or if it's some manner of placebo, but as it seems to work, I'll not complain.