How Long Does the Flu Last and Other Flu FAQs

How Long Does the Flu Last and Other Flu FAQs

Find out the truth about some common myths and misconceptions about influenza.

If you feel like you’re coming down with something, how can you know if you have the flu? You may think it’s COVID-19 or a cold; or if you’re throwing up, you may think it’s the stomach flu. But influenza viruses are different from those that cause COVID-19, colds or tummy troubles. Here are answers to your need-to-know flu FAQs.

1. How are flu symptoms different from COVID-19 or a cold?

Influenza, COVID-19 and colds have similar symptoms, so it can be difficult to tell them apart based on symptoms alone. There are some key differences to keep in mind, however:

  • People with COVID-19 and the flu can experience similar symptoms — such as fever, chills, cough, fatigue, sore throat, runny/stuffy nose and headache — but COVID-19 symptoms can also include loss of taste and smell.
  • While cold and flu symptoms can overlap, colds are usually milder, are less likely to be associated with a fever and are more likely to include sneezing with a stuffy or runny nose.

Infographic comparing flu, cold and COVID-19 symptoms and treatments

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2. How do I know if I have the flu?

Certain symptoms can provide clues, according to Anjali Mahoney, MD, a family medicine physician at Keck Medicine of USC and a clinical associate professor of family medicine at the Keck School of Medicine of USC.

“You may have the flu if you suddenly feel sick with chills, have a temperature over 101°F, are vomiting or have diarrhea,” she says.

If you’re experiencing flu-like symptoms, it’s a good idea to speak to your doctor. And while your doctor may be able to diagnose you based on your symptoms alone, the best way to definitively know if you have the flu is to get tested. This involves a swab of your nose and throat that’s sent out to a laboratory.

Rapid flu tests are also available, but they may be more likely to give a false-negative result — meaning that the test may say you don’t have the flu when you really do. Your doctor will discuss with you whether you need to be tested and what kind of test you should get.

3. How dangerous is the flu?

Not only is the flu common, but it’s also dangerous. According to the Centers For Disease Control and Prevention (CDC), an estimated 8% of Americans get sick with the flu every year, but this can range anywhere from 3% to 11%, depending on the flu season. During the 2018–2019 flu season, the CDC reported that more than 490,000 people in the United States were hospitalized with the flu, and more than 34,000 people died from it.

Data show that children are more likely to come down with the flu than older adults, however, it’s particularly dangerous to both age groups, specifically those younger than 5 years old or those over 65 years old. Pregnant women, people with medical conditions or people with weakened immune systems are also at increased risk.

4. Does the flu vaccine work?

Although it isn’t perfect, the flu vaccine is the best defense we’ve got. Each year, scientists predict which flu strains may be the most common and include those in the vaccine.

“The flu vaccine is effective in 40% to 60% of people, depending on the flu season,” Mahoney says.

So, while some people who get the vaccine may still get the flu, that doesn’t mean they won’t benefit from it. That’s because the flu vaccine can help prevent some of the more severe complications that can occur from the flu, Mahoney explains.

“The flu vaccine is an important prevention measure against hospitalization from the flu,” she adds.

The optimal time to get a flu shot is before it begins spreading in your community. The CDC recommends getting vaccinated in early fall, by the end of October, but if you miss this window, you can still benefit from getting the vaccine as late as January (or even later).

In addition to getting a flu vaccine, practicing good hand hygiene is another great way to protect against the flu. Wash your hands often, and if soap and water aren’t available, use an alcohol-based hand sanitizer. Also, avoid touching your face, as germs can get in through your eyes, nose or throat. Disinfecting surfaces commonly touched by others, such as door handles, can help, as can keeping your distance from people who appear to be sick.

5. How long does the flu last?

Unfortunately, the flu can stick around for a while. Some people may get better within a few days, but the flu can last up to two weeks. Although it’s disruptive to your daily routine, you should stay home and away from people — except to go to the doctor — until you get better in order to avoid spreading it to others: about 24 hours after your fever goes away without fever-reducing meds. You’ll be contagious from about 1 day before showing symptoms to 5 to 7 days after.


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6. What are the treatments for the flu?

One reason to go to the doctor and test for the flu as soon as possible is that the available antiviral medicines are most effective if taken within 48 hours of the onset of symptoms. Antivirals are not the same as antibiotics: Because the flu is a virus, it won’t respond to antibiotics, which only work against bacterial infections.

7. Is the stomach flu the same as the flu?

The stomach flu is actually a misnomer. When you have a stomach bug, or gastroenteritis, it’s caused by viruses such as norovirus or rotavirus (not influenza) or by bacteria or parasites. There’s no treatment for viral gastroenteritis, so you have to let it run its course, which can take up to a week.

by Tina Donvito

Do you have concerns about the flu? Our family medicine clinicians can help. If you are in the Los Angeles area, request an appointment or call (800) USC-CARE (800-872-2273).