I actually kinda believe in that AirBorne stuff. It really seems to head a cold off at the pass, or at least shorten the duration. Almost every doctor I have talked to says it's probably not a whole lot diferent than taking a one a day vitamin, but it sure seems to help me out when I feel something coming on, even if it is purely psychological. Other guys I know swear by Zycam <sp?> a Zinc based stuff. Both kinda spendy, and neither have a particularly enjoyable taste. For me personally, I am prone to sinus infections, as is my sister. She's a nurse, so she picks up all kinds of stuff at work. Even though she similarly has access to free trial size antibiotics, she figured out and passed along to me a preventive measure in that department. Buy SALINE nasal spray (the others can be "addictive") "Ocean Drops" is a brand name but the generic equivalent is far cheaper, and flush your sinuses out with the stuff at the first sign. (This is not a nice-looking process, you'll want to wait until you get to the hotel as opposed to doing it in an airport bathroom.) Get PLENTY of that stuff in there, and roll your head around so it gets in all the nooks and crannies. It will come draining back out with all sorts of pleasant looking stuff. Repeat. Repeat Again. Yes, Susan, it's supposed to burn a little. The salt in the saline may be enough to kill a slight infection, and/or the repeated applications may be enough to flush the infected snot out. Haven't been to a doctor for a sinus infection in awhile now. Also, MAKE SURE to throw the bottle of saline away when you feel better, don't save it for next time.
I also go nowhere without Immodium. Ya never know when you're gonna need a dose of "Liquid Cork" and need it NOW. Between my flight case and my rollabord, I carry enough of that stuff to plug an elephant up for a month and a half.