How Long Is the Flu Contagious? Find Out Here

How long is the flu contagious? Adults may be contagious for 5-7 days after symptoms appear. Children can spread the virus longer, up to 10 days or more.

Doctors say stay home if you catch the flu to keep others safe. It’s key to know how long the flu virus stays contagious. Flu viruses usually spread when sick people cough, sneeze, or talk. If their droplets reach someone’s mouth or nose, they might get the flu. Touching a contaminated surface or object and then your face is another way to get sick.1

A person can spread the flu 1 day before they show symptoms. This can last 5 to 7 days from when they feel ill.1 Kids and those with weak immune systems might spread it for even longer.1 Furthermore, the flu virus can stay alive on surfaces for 48 hours.1

Key Takeaways

  • Flu viruses primarily spread through respiratory droplets from coughing, sneezing, and talking.
  • People with flu are typically contagious 1 day before and 5-7 days after symptoms appear.
  • Children and those with weakened immune systems may be contagious for longer periods.
  • Flu viruses can survive on surfaces for up to 48 hours.
  • Staying home when sick and practicing good hygiene are crucial to prevent flu transmission.

What is Influenza (Flu)?

Influenza, or the flu, is very contagious. It’s a respiratory illness from viruses. These viruses affect the nose, throat, and sometimes the lungs.2 It can make people mildly to very sick. In some cases, it can be fatal.2

Flu Symptoms

Symptoms of the flu come on fast. You might have a fever, chills, cough, or a sore throat. There could be a runny nose, muscle aches, headaches, and you’ll be very tired.3 Kids might have stomach issues like vomiting and diarrhea.3

How Flu Spreads

The flu spreads mostly when people cough, sneeze, or talk. They create tiny droplets. If these droplets land in another person’s mouth or nose, they can get sick too. Sometimes, you can catch the flu by touching something with the virus and then touching your face.3

How Many People Get Sick with Flu Every Year?

On average, about 8 percent of the U.S. population gets the flu each season. The range can be between 3 percent and 11 percent, depending on the year.2 Kids under 18 get the flu more than adults over 65. The average number of kids getting sick is 9.3%. For adults 18-64, it’s 8.8%, and for those over 65, it drops to 3.9%.2

Who is most likely to get sick with flu?

Kids under 18 are the most likely group to catch the flu. Their average number is 9.3%.2 In contrast, adults 65 and older have the lowest incidence at 3.9%.2

How is seasonal incidence of flu estimated?

The number of flu cases is estimated by the CDC using hospitalization rates. These rates are then used to figure out the total number of flu cases for a season. This helps them find out how many people get the flu each year.2

Does seasonal incidence of flu change based on the severity of flu season?

Every year, between 3 percent and 11 percent of people in the U.S. get the flu. How many people get sick changes with the severity of the season. For example, the 2011-2012 season was a mild year with a 3 percent rate. The next year, it jumped to 11 percent. The 2014-2015 season was also severe, with 11 percent getting sick.2

How long is the flu contagious?

A person with the flu can spread it for about 5 to 7 days.3 However, some can spread it up to 10 days or more. This is true mostly for kids and those with weak immune systems.3 The flu virus is detectable a day before symptoms appear. It remains detectable for about five to seven days after getting sick.3 The first 3 days of the illness are when someone is most likely to spread the flu.3

Each year, up to 8% of the U.S gets the flu.2 This rate can vary between 3% and 11%, based on the year.2 Kids, age 0-17, get it the most, with a rate of 9.3%. Adults from 18-64 get it at an 8.8% rate. Those older than 65 have a lower rate of 3.9%.2 The yearly flu rate can be between 3% and 11%, depending on the year’s severity. For example, the 2011-2012 flu season, which was not as severe, had a 3% rate. But severe seasons like 2014-2015 saw an 11% rate.2

The number of flu cases is estimated by looking at CDC flu hospitalization data.2 Flu can be passed to others a day before feeling sick. It can continue to spread up to 5-7 days after, or even longer in some cases.3

Age GroupFlu Incidence Rate
Children (0-17 years)9.3%
Adults (18-64 years)8.8%
Older Adults (65+ years)3.9%

In most cases, the flu is contagious for 5-7 days after symptoms start. But for some, like children and those with weaker immune systems, it can last 10 days or longer.3

flu contagiousness duration

When Are People with Flu Contagious?

Symptoms and Contagiousness Timeline

Most people start spreading flu a day before they feel sick. Then, they can still spread the virus for five to seven days after.3 The peak time for spreading it is within the first 3 days of feeling unwell.4 Others might spread it for longer, especially kids and those with weak immune systems.3

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Signs of the flu show up after about two days of catching the virus. This can happen anywhere from one to four days post-infection.3 There’s a chance someone could pass it to others before they show symptoms.4

Average Flu Incidence in the U.S.About 8% of the population, with a range of 3-11% depending on the season2
Flu Incidence by Age GroupChildren 0-17: 9.3%, Adults 18-64: 8.8%, Adults 65+: 3.9%2
Flu Season DurationTypically starts in fall and lasts through spring in the U.S.3
Flu Symptom Onset1-4 days after exposure to the virus3
Contagious Period1 day before symptoms to 5-7 days after getting sick, longer for some individuals3
Incubation PeriodMost healthy children and adults can infect others starting about one day before symptoms appear, lasting up to seven days after symptoms subside4
Contagious Phase Duration for ImmunocompromisedPeople with weakened immune systems may remain contagious for several weeks4

Person to Person Transmission

Most experts say flu viruses mainly spread through tiny droplets. These come out when someone with flu3 coughs, sneezes, or talks. If these droplets land in someone’s mouth or nose, they could get sick.4 The flu spreads fast when infected people cough, sneeze, or talk. It also spreads by touching things that have the virus on them.4 While not as common, you can get the flu from touching something with the virus and then touching your face.3 Keeping some distance from others reduces your chance of catching or spreading the flu.

Flu Transmission ModesProbability of Transmission
Respiratory DropletsHigh
Contaminated SurfacesLow
Physical DistancingReduces Risk

So, the [flu virus transmission between people] mainly happens through the air. This is when someone infected with the flu breathes out or talks. The virus can also be on things we touch.4 Keeping away from people can reduce how many get sick from the flu.

Viral Shedding and Flu Contagion

Factors Affecting Viral Load

Flu viruses show up in most sick people about a day before they feel symptoms. They can still be found five to seven days later.5 The most contagious time is within the first 3 days of feeling sick. This being said, how bad the illness is, your age, and how strong your immune system is can change this.5 This means that kids and people with weak immune systems might spread the virus longer.5,4

Even after feeling better, flu can still spread for up to a week in healthy adults and kids.4 For those with weaker immune responses, they might still be contagious for weeks.4 A study discovered that kids aged 0–5 can share the virus for the longest time after their symptoms are gone. This was confirmed by research published in The Pediatric Infectious Disease Journal.5

How sick you get, your age, and how strong your immune system is can vary how long you’re contagious with the flu.5,4 People with weaker immune systems or small children may spread the virus for a longer time. This puts others at risk for more extended periods.5,4

Flu Incubation Period and Symptom Onset

Flu symptoms often start two days after getting infected. However, this can vary from one to four days.6 Typically, after being exposed, it takes around two days for symptoms to show.6 In some cases, people can spread the virus to others before they feel sick themselves.6 The flu’s incubation period ranges from one to four days, with an average of two days.6

When flu symptoms appear, the virus is most contagious. This usually happens on the first day of feeling sick.6 People with the flu are usually contagious for five to seven days.6 But, some groups may spread it longer, like children and older adults.6 Flu symptoms can stick around for three to seven days. After that, you might still feel tired or weak for up to two weeks.6

Flu Isolation Guidelines

The7 CDC says if you have the flu, stay home. Don’t go out to avoid getting others sick. Wait it out at home until you’re fever-free for a day without meds.7

CDC Recommendations

If you think you have the flu or know you do, don’t go to work. Stay home for 5 days after you start feeling bad. The first 3 days are when you’re most likely to spread it.7 Don’t go back until you’re feeling better and fever-free for a full day without help from meds.7

Workplace and School Policies

Lots of places like jobs and schools have rules for when you’re sick. They want you to stay home if you might spread the flu.7 It’s a good idea for bosses to share these rules before lots of people get sick.7 Offering different ways to take time off and work can stop the flu from spreading at work.7 If you must stay home to take care of others, bosses should try to be understanding. They might make changes to help you take time off when needed.7 And, training more than one person for each job can keep things running if someone is out sick.7

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Reducing Flu Transmission Risk

To cut down on the flu virus spreading, the CDC advises doing three things. First, keep your hands clean. Second, cover your coughs and sneezes. And third, disinfect things you touch a lot.2 Doing this lowers the chance of spreading the flu to others.

Hand Hygiene

Wash your hands often with soap and water, or use hand sanitizer.8 Make sure to do this after you cough, sneeze, or touch surfaces others might have touched.

Respiratory Etiquette

Use a tissue or your elbow when you cough or sneeze. Throw the tissue away right after.8 This keeps germs off your hands and stops them from getting on things others touch.

Surface Disinfection

Keep things clean that people touch a lot, like doorknobs and desks.8 This stops germs from living on these surfaces and spreading to others.

By doing the right things with your hands, your coughs, and the stuff you touch often, you help keep the flu away from others. You help make your community a healthier place. Plus, it just makes sense to do these easy, helpful steps.

Flu Vaccination and Contagiousness

Getting a flu shot every year is crucial. It helps stop the flu from spreading. The vaccine might not stop you from getting sick, but it makes sure you won’t be as sick for long. This way, you’re less likely to make others sick.


Vaccine Effectiveness

A flu shot lowers your chances of catching the flu, but it’s not a 100% sure thing. This is because the flu virus keeps changing. In a mild flu season like 2011-2012, about 3% of people in the U.S. caught the flu.2

But in seasons with more severe cases, like 2014-2015, around 11% of the population got sick.2

Herd Immunity Benefits

Vaccinating many people doesn’t just protect them, but it shields those who can’t get vaccines. This includes babies and people with weak immune systems.2

Teens and kids have a higher chance of getting the flu than older people. That’s why it’s so important that kids, especially, get vaccinated. They’re more likely to spread the flu if they catch it.2

Antiviral Medications and Flu Contagion

Antiviral drugs like Tamiflu and Xofluza treat flu symptoms. But they can’t stop the virus from spreading. Although these drugs help people get better faster, they are still able to infect others. Thus, even when taking antivirals, someone with the flu can make others sick. The CDC endorses four antiviral drugs for flu treatment. However, this doesn’t mean the virus won’t spread while using them.

People become contagious a day before feeling sick with the flu. This lasts up to seven days into the illness. The highest risk of spreading the virus is in the first few days. Yet, someone with the flu can still be contagious for the whole week. The flu can also spread by touching virus-contaminated surfaces. It can survive on common items, such as doorknobs, for a full day.

Antiviral meds lessen the flu’s harsh effects but they won’t stop its spread. If you have the flu, staying home and avoiding contact with others is crucial. Also, seeking medical advice is important. To prevent the flu’s transmission, simple habits like covering your mouth when you cough or sneeze, staying away from sick people, and washing your hands often are key.

Antiviral MedicationEffectiveness in Reducing Flu Contagiousness
Tamiflu (Oseltamivir)Does not eliminate virus transmission9
Rapivab (Peramivir)Does not eliminate virus transmission9
Relenza (Zanamivir)Does not eliminate virus transmission9
Xofluza (Baloxavir marboxil)Does not eliminate virus transmission9

Antiviral drugs can cut the flu’s effects but not its spread.9 When you have the flu, care for others by staying home and following good hygiene. Annual flu shots and tips from the CDC are best for stopping the flu’s spread.3

High-Risk Groups and Flu Contagiousness

Some people have a higher risk of serious flu complications. They might also spread the virus more.

Children and Flu Transmission

Kids under 18 often catch the flu and can spread it longer than grown-ups.2Between 0-17 years, the chance of getting the flu is 9.3%. This is over twice the rate for those 65+ at 3.9%.


Elderly and Compromised Immune Systems

Older adults and people with weak immune systems face a bigger risk from the flu. They can shed the virus for a longer time, putting others in danger.

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Each year, around 8% of Americans catch the flu. The number swings between 3% to 11%, depending on the flu’s strength.2 Young kids, the elderly, and those with weak immune systems get hit hardest.3 They might stay contagious longer than most people.10

Flu Symptoms Timeline: From Onset to Recovery

Flu symptoms usually show up after about two days from catching the virus. They can start anywhere from one to four days after.11 You might spread the virus to others even before you feel sick.11 Most folks will have a mix of issues like fever, cough, and muscle aches.12

It might take 1-2 weeks to feel fully better. But, a cough and feeling tired might stick around longer.12 You can spread the flu to others for about seven days, with the most risk on days three and four.11 Kids might be able to spread it for more than a week since their immune systems aren’t as strong.11

After being exposed, it could take one to four days to get symptoms. Then, it might take another five to seven days to fully recover.11 Medicines for the flu can make you feel better faster by a couple of days. But, they must be taken within the first 48 hours of showing symptoms.12 Drugs like oseltamivir (Tamiflu) can help you bounce back quicker.12


The flu virus stays contagious for 5-7 days after symptoms show in most people.13 Yet, kids and those with weaker immune systems could spread it for over 10 days.14 It mainly spreads through coughs, sneezes, or talking, and by touching things then your face.13 To lower the spread, follow CDC advice: stay home when sick, wash hands well, and get a yearly flu shot.14

The flu spreads most in the first 3-4 days after you feel sick,13 but you might still infect others for 5-7 days after.13 Start antivirals within 48 hours for the best effect,13 and OTC meds can help with symptoms.13 Drink lots of water, broth, or herbal teas for a fast recovery.13

Adults with flu A can spread it a day before symptoms to 5-7 days after getting sick.14 Kids and those with weak immune systems might be able to spread it longer.14 The flu vaccine cuts the chance of getting sick by 40% to 60%.14 Everyone aged 6 months and up should get the flu shot every year to fight influenza A.14


How long is the flu contagious?

A person with the flu can spread it for 5 to 7 days after symptoms start. Children and those with weak immune systems might spread it up to 10 days.

When are people with the flu most contagious?

The flu spreads a lot within the first 3 days of feeling sick. The virus can even start spreading the day before symptoms show up, lasting for about 5 to 7 days after.

How does the flu virus spread from person to person?

Flu mainly spreads through droplets when an infected person coughs, sneezes, or talks. These droplets can enter others’ mouths or noses. It’s less common but possible to get the flu by touching something with the virus on it, then touching your face.

What factors affect how contagious someone with the flu is?

The severity of the illness, age, and immune strength affect how contagious a person is. Those with weak immunity or kids might spread the virus for a longer time.

How long is the flu incubation period?

The time between getting the virus and showing symptoms is typically 2 days. But it can range from 1 to 4 days. Even without symptoms, people can pass the flu to others.

What are the CDC recommendations for isolating people with the flu?

The CDC says it’s best for flu patients to stay away from others. This means not leaving home except for medical help. Wait at least 24 hours after fever ends without medicine before being around people again.

How can I reduce the risk of spreading the flu?

The CDC advises washing hands often, covering coughs, and cleaning frequently touched surfaces. Also, flu shots are very effective at preventing flu and lessening how much it spreads.

Do antiviral medications stop the spread of the flu virus?

Antivirals don’t stop flu spread but can help treat it. Even if people take these, they can still infect others. Yet, antivirals may make the sick period shorter.

Which groups are at higher risk of being more contagious with the flu?

Kids under 18 often get and spread the flu more than adults. The elderly and those with weakened immune systems can also shed the virus longer. This increases the risk for people around them.

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