How Long Is the Flu Contagious?

Caucasian boy blowing nose in classroom
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None of us want to get the flu, but when it pops up somewhere it seems to spread like wildfire. One person in your office comes into work sick and the next thing you know, half of the employees are calling in sick or coughing and sneezing at their desks. 

So just how contagious is the flu? When should you avoid other people if you are sick?

How Long Is the Flu Contagious?

Contagious means that an illness can pass from one person to another making them sick.

Exactly when you are contagious depends on the virus or bacteria that is making you sick.

If you truly have influenza - the flu - it is typically considered to be contagious from one day before you develop symptoms through 5 to 7 days after symptoms start.

To make matters a little more complicated, kids can spread the virus for longer - more than 7 days in some cases.

One of the reasons the flu spreads so rapidly is because it is contagious before you know you have it. That means you could be exposed to the virus one day, two days later you are spreading it to other people around you, but you don't get that "hit by a truck" feeling until the third day. It's a difficult thing to control once it is in your workplace, school or community.

What You Can Do

If you are diagnosed with the flu, stay home. Don't try to go to work and definitely don't send your child to school if she is sick.

Doing that only puts other people at risk - including those who may not recover from it as easily as you. 

Talk to your health care provider about treatment options. If you are at high risk for flu complications, your doctor may decide to prescribe an antiviral medication to help decrease the severity of the symptoms and the duration of the illness.

It's important to know that taking antiviral medications will not change whether or not you are contagious. Unlike antibiotics, which kill bacteria and stop you from spreading the illness after about 24 hours of starting it, antiviral medications do not kill influenza. You will still be contagious even if you are taking one of these medications.

Cover your cough. Even if you are not around many people, coughing can spread your germs up to six feet and the invisible droplets that come out of your body when you cough can make others sick. Coughing into your elbow will help prevent some of that and doesn't just transfer the germs onto your hands. When you cough into your hands, you pass the germs onto everything you touch, making it easier for others to come into contact with those germs when they touch those objects after you. 

Clean, clean, clean. Try to stay away from others in your household when you are sick with the flu. If you can manage it, clean common items in the household as often as possible to avoid spreading germs. Things like doorknobs, remote controls and cell phones are touched often but rarely cleaned. 

If you have the flu, do your best to stay away from other people as long as you are contagious - or likely to be.

You never know how the virus may affect someone else.


"How Flu Spreads" Seasonal Influenza (Flu) 30 Jun 11. US Centers for Disease Control and Prevention. 22 Mar 12.

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