Fever, chills, cough, sore throat, running nose and body aches.

If these symptoms sound familiar, you could be fighting the flu. But how can you tell whether the source of your ailments are the flu or just a bad cold, maybe even allergies?

"Sometimes it's difficult to tell," said Dr. Alan Mensch, a pulmonologist who is also senior vice president of medical affairs at Syosset and Plainview hospitals.

"It's much easier when we know there's flu around; when it's epidemic it's easier to spot," he said, but added that hasn't been the case on Long Island this flu season.

Though local cases of the flu have gone up in recent weeks, he said, it hasn't reached epidemic proportions.

So another way doctors decode whether a patient could be suffering from the flu is to assess how quickly the symptoms surfaced. While cold symptoms tend to arise gradually, the flu usually strikes abruptly within a day or even a few hours, he said.

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Flu sufferers often experience some or all of the following symptoms, according to the Centers for Disease Control and Prevention:

  • Fever or feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue
  • Vomiting or diarrhea (This is more common in children than adults.)

Influenza is a contagious respiratory illness. "Generally, you're contagious about 24 to 48 hours before you notice symptoms ... and most people shed the virus for about five days," Mensch said.

It can spread through the air by cough or sneeze, or by touching surfaces that have been contaminated with the germs, he added.

Most people who catch the flu recover in anywhere from a few days to less than two weeks, according to the CDC, but some people will develop complications (such as pneumonia) as a result of the flu, which can be life-threatening and even result in death.

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Mensch recommended those experiencing flu-like symptoms to contact their doctor. Their physician may prescribe a drug called Tamiflu, but Mensch said it needs to be taken within the first 24 to 48 hours to be effective, and since it isn't a cure, it will only shorten the duration of the flu.

Most people are able to fight off the flu by resting at home and taking Tylenol or Motrin to combat some of the symptoms, he said.

And despite popular beliefs, looking at your own mucus will not help you decipher whether you have a cold, allergies or the flu nor indicate whether or not you're closer to recovery.

Mensch adds, "The color means very little."