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A full 80 percent of people go to the office when they know they're ill, finds Staples' annual Flu Season Survey.

This can prolong recovery time, not to mention expose colleagues to germs. Ideally, you'd take off that first day (when you're most contagious), even if it's just a cold.

And if you have any of the signs below, you must skip work and go to the doctor—no ifs, ands, or buts:

1. A fever of 100.4 degrees or higher.

2. A prolonged sore throat with painful swallowing and swollen glands (without congestion or cough).

3. Any symptoms that haven't improved after a week.

4. Nasal congestion along with one-sided facial pain, a toothache, or dark-colored mucus (this might be a sinus infection).

5. Nausea and vomiting.

Can't get to the doctor right away? Good news: There's an app for that!

We all have those moments when we wish we had an MD pal on speed dial. Free smartphone app HealthTap makes a good fill-in: It lets you submit any health question to a network of 14,000-plus U.S.-licensed physicians, one (or more) of whom will get back to you with an expert opinion.

While any question is fair game, and you can even upload medical documents and test results in HIPAA-secure exchanges with docs, Health magazine's medical editor Roshini Rajapaksa, MD, recommends sticking to queries that don't require a face-to-face appointment, like Can I take this antibiotic if I'm on the Pill? Within a few hours you'll have a well-informed answer—no circuitous Internet searches required.

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