I have a recommendation that works.
I know it is expensive (like $15 a bottle), but I am telling you that Zicam works. If you are starting to get a cold, and you take it as directed, you will not get sick. You will feel 99% better in 2 days.
You have to catch it early, but for me $15 is worth not getting a cold and feeling terrible for 2 weeks. Also, I don't really have a job that allows me to be sick.