Dont use hand sanitizer or antibiotics every five minutes...not gonna help you now but I think people over sanitize everything and its weakened everyone's immune systems. If you're around sickness, keep your distance and wash your hands frequently. Take vitamin c.
I think a lot of it is psychological. The body will only absorb as much Vitamin C as it needs, so I know where you're coming from, but I can also say that I've used it before and prevented sickness. Home remedies are half truth, and half mindset...or maybe just superstition, I dunno. What would you do?
Now that you say that, my dad used to take zinc. Not sure if it helped him or not, but he doesn't use it anymore, so who knows. True dat on the soup and peppers, spoonful of chinese mustard or wasabi would do the trick too if you could stand it, lol
Cold and Flu: 10 Ways to Feel Better Fast - WebMD Symptom Checker
I tried to make a link to the site, but it was difficult, so I guess you could type it on the search engine? I know you only said he had a cold, but it works for both.