+1 on the "use your sick leave"

Differentiate between the cold that leaves you sniffling / stuffy nose / coughing vs something with a fever that makes it hard to do anything (e.g. standing and balancing yourself).

If you're just miserable with sniffling or what not, concentrating on something could take your mind off from it.

But still, I'd get some rest and make the whole thing pass by faster instead.