One word: ZINC
Explain, please!
https://www.webmd.com/cold-and-flu/news/20110215/zinc-may-prevent-and-shorten-colds#1
http://www.health.com/cold-flu-sinus/4-things-you-should-know-about-zinc-and-the-common-cold
It is not a cure, but it does knock a down and you get better quicker.