Astute Reader and Amazing Vocal Coach Marissa Dockery, wrote in with a very solid point about Vocalists using Airborne and Emergen-C. Check it out below:
Regarding sickness and fancy over the counter remedies from a vocal perspective, I tend to think that less is more. Airborne, Emergen-C, and other vitamin cocktails are huge dosages of vitamins, which often dry out the throat and mouth, adding another obstacle to preexisting congestion. Small amounts of vitamin c (maybe 250 mg) every couple of hours while keeping well hydrated with room temperature water is a better approach. I also recommend tea, Epsom salt baths, keeping the body warm, resting, and eating well, staying away from dairy and sugar. Ideally, take a few days off if you can, you will be better for it.