I hate it when I get a cold!  As soon as I get the sniffles I take Vitamin C to fight it.
That's a good idea. There is some evidence that regular use may shorten how long a cold lasts.
I just take whatever amount is in a vitamin.  How much should you take?
You might want to read that bottle. I'm not exactly sure of the correct dosage, but too much may cause stomach discomfort, headaches, trouble sleeping and skin flushing.