Personally I've never really relied on Tussin and all that crap thats out there. I'm like the old fashioned guy, when I get sick I dedicate 2 days to sleep and getting better as much as possible. Usually all other things can wait a few days even work and school, but I realize some things come up that cannot wait so I get those out of the way ASAP. I drink lots of hot tea with plenty of lemon, when I'm sick I eat almost nothing but if I do its something home made and warm, and this year I also started taking "Airborne"(sp?).
I almost never get sick and when I do its usually for 2 days out of the year, and by the second day I usually feel a whole lot better.
If your symptoms get bad take a Tylenol and try to get some sleep.
But yeah in general if your sick, don't bother try to do everything you normally would, you'll only end up prolonging your own misery.