How Long Is the Flu Contagious?

Doctors tell you to stay home when you have the flu so you don’t get other people sick. But how long do you have to shut yourself away? Here’s how to know when you can be out and about again.

How long can I spread it?

About a week. You’re contagious from 1 day before you have any symptoms. You stay that way for 5 to 7 days after you start feeling sick. Kids may be able to spread the virus for even longer, until all of their symptoms fade.

How do I spread it?

Most of the time, it’s through droplets in the air. Sick people sneeze or cough out beads of moisture that contain the flu virus. They can travel up to 6 feet. You’re exposed to the flu virus when you breathe the droplets in, or if they land in your mouth, nose, or eyes. You can also get it if you touch a place those droplets land -- like a desk, counter, or doorknob -- and then touch your face. The virus can live on hard surfaces for up to 48 hours.

When am I most contagious?

Some experts believe you’re most likely to spread the virus from the first day of symptoms through the next 3 to 7 days. That’s because the more you cough and sneeze, the more droplets you shoot into the air and onto objects around you.

Is there a way to tell if I’m still contagious?

Fever is a definite sign. You should stay home for at least 24 hours after your temperature goes back down on its own. That means without the help of medicines.

Do flu medicines help stop the spread?

No. You can still make other people sick even if you’re taking antiviral mediations that treat the flu. The CDC recommends three FDA-approved drugs to treat the flu: oseltamivir (Tamiflu), peramivir (Rapivab), and zanamivir (Relenza). These drugs could shorten the time that you’re sick. And they might shorten the length of time that you can spread the flu.

The Bottom Line:

When it comes to the flu, an ounce of prevention really is worth a pound of cure. Listen to your doctor: Stay away from people when you’re sick, even if you feel better. It’s the only way not to spread the flu.

WebMD Medical Reference Reviewed by Nayana Ambardekar, MD on October 29, 2017

Sources

SOURCES:

CDC: “How Flu Spreads,” “Flu & You.”

Cowling, B. PLOSOne, published online May 7, 2008.

Halloran, M. American Journal of Epidemiology, Jan. 15, 2007.

Hayward, A. Clinical Infectious Diseases, March 2010.
KidsHealth: “Influenza (Flu).”

Medscape: “Influenza Practice Essentials.”

U.S. Department of Health and Human Services Flu.gov: “Interim Guidance on Environmental Management of Pandemic Influenza Virus.”

UK National Health Service NHS Choices: “Flu.”

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