Ugh. You know the feeling. Chills, sore throat, that sense of "I sure could use a nap right now." Yep, you're probably coming down with something. Sometimes it's hard to tell if it's just a bad cold or you've got the full-on flu.

"A true flu, as in influenza, is a serious viral infection," says Dr. David Shute. "Usually people have a high fever," he says. "as well as fatigue and general aches and pains. For patients who are elderly, very young, or have compromised immune systems, having the flu can be life threatening and require weeks of recovery."

A cold or other viral upper respiratory infections is less serious, and the symptoms are typically less severe.

So what to do to take care of yourself during flu season. "Get a flu shot, if you haven't already," Dr. Shute advises. "A flu shot is the most effective way to protect yourself from getting influenza."

You've gotten your flu shot, already? Good for you--and keep in mind it won't protect you from getting other upper respiratory infections, he adds.

If you do get sick, Dr. Shute recommends taking acetaminophen (Tylenol), ibuprophen (Advil) or naproxen sodium (Aleve) for aches, pains, headaches and other mild symptoms. For stuffed up noses, try an over-the-counter decongestant, like phenylephrine (Sudafed PE), and for coughing, an over-the-counter cough suppressant like dextromethorphan (Robitussin).

But what if it is influenza? "Please call your clinician or send them a secure message," Dr. Shute suggests, "to see if you might benefit from an antiviral treatment. The most important thing you can get extra rest and take care of yourself."

Click here for a short primer: "What's the Difference Between a Cold and the Flu?"