I never travel without
Airborne
Airborne is the best-selling herbal health formula that boosts your immune system to help your body combat germs. It was created by a former second-grade school teacher, Victoria Knight-McDowell, who was constantly exposed to germs in her classroom. Its unique blend of herbal extracts, vitamins, electrolytes, amino acids and antioxidants helps give your body a fighting chance when exposed to germ-filled environments.
I like the lemon-lime flavor - I find it kind of tastes like Sprite. I like to have one before I get on a plane, or if I feel like I'm starting to come down with something. I think you can get a free sample on their website; but pretty much every major grocery/drugstore chain carries it. ^