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Here’s How Dangerous the Flu Can Be

Influenza puts stress on your body and can lead to serious conditions like pneumonia or stroke

Woman with protective face mask huddling on floor while flu spores float around in the air.

Newer illnesses like COVID-19 may grab headlines, but old-and-familiar ailments such as influenza, or the flu, remain a serious health concern — a fact that many might learn during the upcoming flu season.

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According to CDC estimates, tens of millions of Americans get the flu each year. Yet despite those numbers, the flu often gets talked about as if it’s little more than the sniffles. That’s a serious underestimation of the illness, cautions infectious disease specialist Kristin Englund, MD.

“The flu taxes your body in ways that the common cold doesn't", says Dr. Englund. "There’s a lot of stress put on your system as it works to fight off the infection — and that can lead to all sorts of complications.”

With so many symptoms in common, it can be hard to tell the difference between a cold and the flu. Here’s how to tell which is which.

How dangerous is the flu?

So, why is influenza sometimes mislabeled as a cold? Well, the viruses share symptoms such as a cough, fever and an overall cruddy feeling. But with the flu, symptoms often hit harder and last longer.

“Perfectly healthy people can get severe complications from influenza,” says Dr. Englund. “But if you have any underlying health issues, the risk becomes much greater.”

In severe cases, the flu can lead to:

  • Pneumonia and bacterial pneumonia, which can lead to respiratory failure and ventilator use. Dr. Englund calls pneumonia “the No. 1 complication” seen from the flu.
  • A heart attack or cardiac issues such as myocarditis (inflammation of the heart muscle).
  • Stroke.

Somewhere between 3% and 11% of the U.S. population — which represents millions upon millions of people — get infected with influenza every year, says the CDC. Most will recover within three to seven days, though some may see symptoms last a few weeks.

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But your risk for developing severe flu complications increases if you have:

In addition, people at opposite ends of the age spectrum — those younger than 5 years old or older than 65 — tend to be more vulnerable when it comes to flu-related complications. Ditto for those who are pregnant.

Why you should get the flu shot

Healthcare providers often encourage people to consider the flu vaccine as a way to lower their odds of serious illness.

“While no vaccine offers totally protection, research suggests that flu shots can reduce both the chances of infection and the severity if you do catch the virus,” explains Dr. Englund.

According to CDC estimates, flu vaccinations in the 2021–2022 season helped prevent more than a million medical visits and tens of thousands of hospitalizations. Other studies have found that people who were vaccinated had lower rates of ICU admissions and deaths from influenza.

For those who want extra protection — especially older adults, young children, or people managing chronic health conditions — the flu shot can be one useful tool alongside healthy habits like diet, exercise, and good hygiene.

(And to clear up a common misconception: the flu vaccine itself does not cause the flu.)

Other ways to prevent the flu

Want to keep the flu bug at bay this flu season? Aside from getting your flu shot, your overall health choices – diet, exercise, sleep and managing chronic conditions – play a huge role in how well your body can handle flu season. Consider these tips:

  • Wear a mask. The flu spreads quickly through droplets made by people who cough, sneeze or talk while they’re infected. Some people choose to wear masks in crowded indoor settings during peak flu season.
  • Practicing good hand hygiene. Washing your hands thoroughly limits the possibility of transferring the virus from a surface — a doorknob, perhaps — to your mouth or nose.
  • Avoid contact with people who are sick. Be cautious at large gatherings during the peak months of flu season, typically December through February. Maybe go with a friendly wave or fist bump over a hearty handshake. And stay home if you’re feeling unwell — your friends and family will understand.
  • Live healthy. Taking care of your overall health with diet and exercise can help strengthen your immune system and fortify your body to fight off infection.

Despite best efforts, it’s still possible you may get the virus. Don’t ignore flu-like symptoms like fever, cough and body aches. Talk to a healthcare provider right away, especially if you’re in a high-risk group.

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Quick action could allow you to benefit from antiviral medications, which can lessen flu symptoms and help you bounce back a little more quickly.

Final flu thoughts

The bottom line? The flu deserves to be taken seriously.

“We see so many people in hospitals every year because of influenza,” emphasizes Dr. Englund. “People die from the virus every year, too. It’s not something to ignore, so take the precautions you can to stay healthy.”

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