woman blowing her nose(Photo: Paula Thomas; Flickr; Getty Images)

But if it's a weekday, the decision you have to make--call out or head in--is as stressful and confusing as the time you had to figure out what to do with your boss's Facebook friend request.

Turns out, according to the Flu Season Survey from Staples, nearly 80 percent of office workers head to the office when they're feeling sick, even if they know they're contagious. And this, experts warn, is a bad move--not just for you, but for your coworkers, too.

"We've all heard about absenteeism, but presenteeism, or heading to work when you know you're not well, is even more of an epidemic," says Louis Papa, MD, Professor of Clinical Medicine at the University of Rochester School of Medicine. "Not only does pushing yourself through the day stress your body and cause a cold or flu to linger, but it also rapidly spreads germs to people in close proximity."

Related: Facts to keep you healthy this flu season

That said, even experts concede that it's unrealistic to call in for every single sniffle. Here, how to suss out whether you should crawl under the covers or click on the coffee pot and suck it up.