What's the Difference Between a Cold and the Flu? Doctors Explain

They share many symptoms, but the common cold and the flu are not the same thing, as these doctors explain.

couple suffering with flu while sitting wrapped in blankets on the sofa at home, throwing tissues on coffee table
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The latest flu season has been brutal so far, with 6.4 million people coming down with the illness, according to a Dec. 2019 report from the Centers for Disease Control and Prevention (CDC). But how do you know if you're dealing with the flu or just a regular ole cold? Because they are both viral and share many symptoms—sneezing, coughing, and congestion, to name a few—the two sicknesses are often mistaken for one another. But there are quite a few differences between a cold and the flu, according to doctors who deal with them regularly. It all starts with how fast your symptoms surface and which parts of your body they affect.

"The flu tends to be much more severe than a cold and is more invasive to many parts of the body," says Daniel McGee, MD, pediatric hospitalist at Helen DeVos Children's Hospital in Grand Rapids, Michigan. He notes that the quickness of the illness is a diversifying factor that helps in its diagnosis. "The trademark indication of the flu is the sudden onset of fever, achiness, and fatigue," he says. If you experience a gradual onset of symptoms, then it's more likely you're dealing with a common cold.

Not only do the symptoms of the flu come on quicker, but they also tend to take over your whole body, whereas colds are mainly in your sinuses. "The key difference is that a cold will primarily impact the respiratory system, with sinus congestion and resulting runny nose, sore throat, and sneezing," says Darryl Anderson, MD, director of the medical program at Plaza College in Forest Hills, New York. "With the flu, aching throughout the body occurs more often, along with chills and fatigue or weakness."

While doctors may be able to diagnose you by asking questions about your symptoms, they can also run tests to confirm what illness you have. "If necessary, there are nasal swabs or washes that can get a definitive diagnosis," says McGee.

Once your diagnosis is in, it's time for treatment—and the way you take care of your cold versus the flu are also very different. For a cold, you'll likely end up with a suggestion from your doctor to get rest and drink plenty of water. "It's viral and you'll just have to ride it out with over-the-counter medications like decongestants and pain relievers," says McGee. While the flu may have harsher symptoms, it's also a virus, so antibiotics wouldn't help. "You may receive a prescription for an antiviral medication commonly known as Tamiflu, which can shorten the duration of your illness," says McGee.

Because the flu can stick around for a few weeks, there is also a risk of other complications, such as sinus infections or pneumonia, McGee notes. Unlike a cold or the flu, these can be treated with antibiotics.

While you may get a cold or the flu at any point during the year, the winter months are the most concentrated flu season, says Anderson, because that's "when we spend more time indoors and are exposed to more viruses. In addition, many viruses thrive in cold air."

The best thing you can do for yourself? Get the flu shot, which the CDC recommends doing by the end of October every year. "Getting vaccinated later, however, can still be beneficial and vaccination should continue to be offered throughout the flu season, even into January or later," they note on their website.

And if you're worried about the flu shot upending your immune system, that's not usually the case, says McGee. "Contrary to what naysayers believe, the vaccine won't give you the flu," he explains. "If you feel a bit sluggish after receiving it, that's because your immune system is kicking in to fight it." And for more information on handling the common cold, here are The 23 Worst Things You Can Do if You Have a Cold, According to Doctors.

Adam Shalvey
Adam Shalvey is a writer based in Rhode Island. Read more
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