I used to get a pretty bad throat infection every year, that would last for a couple of weeks. Funnily enough, they've stopped now that I lo-carb. I still ocassionally get a little tickle in my throat (but certainly not every year), but it's usually gone in a day or two.
Best thing for it is to just drink LOADS of cold water...
Now - here's a funny thing... If I eat a bar of milk chocolate now that I lo-carb, it actually burns my throat. A very strange sensation.