Lots of my patients have been struck by a miserable cold in the last few weeks. My phone is ringing off the hook (is that a meaningful idiom anymore?) with woeful tales of coughs and runny noses and fatigue and despair. I thought it would be a perfect time to do a little teaching about the common cold, how to treat it, and other diagnoses that it can be mistaken for. But it turns out I already wrote that pos...