10 Signs Your Flu Might Be Deadly

Updated: Dec. 23, 2020

The Centers for Disease Control and Prevention reported that 80,000 people died from the flu in the 2017-2018 flu season. Here's what you need to know to stay safe this season.

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The flu is no joke

People often use “the flu” as shorthand for a lot of different illnesses but when medical professionals say “flu,” they mean influenza—and it’s important to know the difference. The flu is a contagious respiratory illness that’s caused by influenza viruses, sickening nearly half a million people and killing nearly 80,000 in the US during the 2017-2018 flu season, according to the Centers for Disease Control and Prevention (CDC). Because it can be so deadly, it’s important to know what’s normal with the flu and when you need to see a doctor immediately. (Here’s how to tell the difference between Covid-19 and flu symptoms.)

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What is the flu?

There are three types of influenza viruses that cause illness in humans: influenza A, influenza B, and influenza C (though infections by C are mild). Influenza A can be broken down into different subtypes while B doesn’t have subtypes, but it does have various lineages and strains. All of that adds up to several types of bugs that can make you sick each flu season, according to the CDC. Find out which is worse: flu a vs. flu b.

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What are the symptoms of the flu?

It can be difficult to determine whether you’ve come down with the flu or a cold—though one telltale is the severity of your symptoms. Cold symptoms such as a runny or stuffy nose, and a sore throat, will be much milder than flu symptoms, which include the symptoms of a cold plus a fever, chills, headaches, and extreme fatigue, according to Kristine Arthur, MD, an internist at Memorial Care Medical Group in Fountain Valley, California. If you think you might have the flu, it’s important to see your doctor who can run tests for the virus, she adds. Check out these situations that make you think you have the flu but don’t.

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What about the stomach flu?

The stomach flu is not influenza. Known as gastroenteritis flu, this can also be caused by a virus—most commonly rotavirus and norovirus, says Niket Sonpal, MD, an NYC-based internist and gastroenterologist. “With gastroenteritis, the main symptoms someone will have include watery diarrhea and vomiting,” he says. “You might also have stomach pain, cramping, fever, nausea, and a headache.” While these illnesses are relatively mild (although certainly not fun) in most adults, if you become dehydrated or experience symptoms for more than a day or two, things might be turning serious and it’s time to call your doc, he says. Find out 8 ways to prevent getting the stomach flu.

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You get a secondary infection

The influenza virus can become deadly when it triggers a sickness like pneumonia—inflammation of the air sacs in the lungs which may then fill with fluid, Dr. Arthur says. The subsequent infection can be deadly. Other serious conditions that can lead to life-threatening infections include inflammation of the heart (myocarditis), brain (encephalitis), and sepsis—the body’s response to infection which triggers inflammation throughout the body and can result in organ failure or death. Keep track of the following signs to know if your flu is becoming more dangerous:

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Difficulty breathing

Having a hard time breathing normally—or feeling unusually short of breath—are signs that you’re experiencing flu complications, says Dr. Sonpal. . This is more than a stuffy nose that makes it hard to breathe. An infection like pneumonia makes it a struggle for you to fill your lungs; you’ll be unable to take long deep breaths. Breathing complications are more common in people with asthma or COPD.

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Chest or abdominal pain

If you experience chest pain, says Dr. Sonpal, you should consider a trip to the ER to rule out heart trouble. This could be a sign of infection such as myocarditis (inflammation of the heart) or pericarditis (inflammation of the sac around the heart). If you suffer from a preexisting heart issue like congestive heart failure, an infection resulting from the flu could make conditions worse. Read how this man’s “cold” turned out to be a massive heart attack.

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Sudden dizziness or confusion

While a high fever can leave you feeling a little disoriented, extreme dizziness, cognitive problems, and confusion can be a sign of infection, Dr. Arthur says. It’s important to get checked out immediately if you start to experience any such signs. And check out these flu-prevention strategies.

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Severe or persistent vomiting

Any vomiting from the flu should only last a day or two so if it’s been longer than that, or if you’re vomiting blood or have a fever above 104 degrees Fahrenheit, or you can’t keep liquids down for longer than a day, you should call your doctor immediately, Dr. Sonpal says. (Keep these flu memes handy if you get sick and need a laugh.)

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You’re a certain age or size

Senior citizens (over the age of 65) and people who are overweight or obese are more likely to get the flu and to suffer serious complications from it, warns Dr. Sonpal. These groups tend to have weaker immune systems and a lower immune response to viruses, and can, therefore, be at risk for complications, the CDC says. Be on your guard by making sure you know these ways to tell that flu season is in full effect.

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You have a medical condition or are pregnant

Having the flu when you’re healthy is hard enough but add in a chronic medical condition or pregnancy and you’re at a much higher risk for serious complications, Dr. Sonpal says. “Being pregnant or having a chronic lung disease such as asthma, chronic obstructive pulmonary disease (COPD), bronchiectasis, and cystic fibrosis are among the diseases that place someone at high risk for developing flu complications,” he explains. People who are pregnant are at greater risk of serious flu complications compared with people the same age who are not pregnant, according to the CDC.

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You’re an infant

Kids under the age of five years old—and particularly babies under two years of age—are at high risk of flu complications as well, warns the CDC. Parents: If you notice your infant has trouble breathing, has changes in skin tone to a bluish color, is extremely irritable, has a fever with a rash, is avoiding liquids, or has flu symptoms that improve but then get worse with a fever and cough, you should call your doctor immediately, Dr. Arthur says. Here are 10 cold and flu remedies for kids all parents and caregivers should know.

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For infants err on the side of caution

Infants are still developing their immune system, so if you think a baby under two years old has the flu, you should seek medical help immediately, especially if they having difficulty breathing or eating, produce no tears when crying, or have significantly fewer wet diapers than normal, Dr. Arthur says. It’s always better to be safe than sorry with age group, she adds.

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How to protect yourself from the flu

The absolute best defense against the flu is to get an annual flu shot, Dr. Arthur says. The CDC recommends that everyone from six months of age and older gets vaccinated every year to reduce the risk of contracting the flu. If you do have the flu, talk to your doctor if you should take antiviral medications (like Tamiflu) to help shorten the time you’re sick or prevent complications. Check out these 10 natural flu remedies for symptom relief.