As a diver, catching a cold is pretty much the end of the world for me. Blocked sinuses and eustachian tubes would keep me out of the water for 2 or 3 weeks. So I've taken great interest in this and experimented over the years with exercise vs rest and come to the conclusion that several days of rest, during the phase when you're feeling worst, generally reduces the duration of the cold. Translating this to running - if you carry on exercising, you'll only do it half heartedly and gain little of value from the training. If you rest and let the cold run its course more quickly, you'll then very soon recover any lost ground.

One other thing; I've never been one for spending money on dodgy herbal "remedies". But I used to be a teacher, which involved spending time with large numbers of youngsters doing their best to sneeze in my face. So I would typically catch at least 3 colds each year. Then someone suggested I tried using Echinacea tablets as a preventive measure during the colds season. I took some persuading to try this but, when I did, I found I only got one cold a year on average. I also think (but I'm not certain) that the duration of these colds may have been slightly less than formerly. I believe the science behind this is very shaky but - what works works, I guess.