But if you do need a cure try these tips.
Why they work
You'll notice that all of them are trying to change the pH of your internal and external environments. Your body naturally balances your pH extremely well (between 7.38 and 7.42 - slightly alkaline). It is easy to increase your alkaline balance by decreasing your CO2 levels (breathing exercises and increased respiration). If you increase your acidic intake internally (apple cider vinegar, orange juice or other vitamin C source eg. citric acid), your body will respond with an alkaline response, killing the bad guys and restoring your immune system. Externally you need to create an alkaline environment (saline sinus and oral rinsing).
Since your body regulates your pH all day it would seem to be the best approach works best in multiple, small doses. I'm proud to say I have had only two mild colds since understanding and applying this science 12 years ago... in addition to a couple other tricks I've picked up along the way.