In case you haven't been watching the news, there is a flu epidemic being reported across the United States, and even if you haven't caught it yet, chances are you either will or you know someone who has been sick.But even if you wake up in the morning and feel kind of weak, how do you know if you're sick enough to stay home? After all, many people work in offices where people who use up sick days are looked upon suspiciously and made to feel like slackers if they take a day off.Offices like these, though, who discourage people taking days off are often the ones with the most ill employees. And aside from the health issues, a sick employee is a non-productive one. So if you're sick and your company pays for your sick days, use them. Just don't waste them – because you never know when you'll really need that sick day you wasted last spring when the weather was just too nice to go to work.Who among us hasn't done that? Be honest.But there are a few things you should watch out for when deciding if you need to say home from work. Doctors generally agree that you should stay home if you have a temperature of 100 or higher, you're coughing or sneezing often, or if you have vomiting or diarrhea.The cold or flu is most contagious in the first 24 hours, so if you wake up feeling sick, that's the day you should stay home, not when you've worked and worn yourself out later in the week.If you insist on going to work, though, take some precautions to keep your co-workers from getting sick too.Wash your hands often with soap and water and keep a hand sanitizer at your desk. (not a bad idea for people who aren't sick, too, as a preventative measure.If you have to sneeze or cough, do it into a tissue or your sleeve. When you sneeze into your hand and then touch things, you're spreading germs.Keep several feet away from others. A sneeze or cough can propel your germs, through your saliva, between six to eight feet.Basically, use your best judgment. If your cubicle mate would look and sound like you, and it would annoy you if that person came to work, then maybe you should consider calling off as well.