If it is a bad cold then rest, apart from feeling rough you could be putting extra strain on your heart and muscles in general. If you want to keep training knock off the really hard stuff for a few days, you won't lose form in that time and will recover quicker from the cold thus getting you back training at full tilt earlier. Never mask the illness or any illness with painkillers since you will damage yourself without knowing. You are likely to dehydrate if cycling with a cold also since you will be running a high temperature also.
Take a 3 days off, watch le tour and drink that orange juice.