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Cold, Flu, & Cough Health Center

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Flu Test: How to Find the Virus

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A doctor can usually tell if you have the flu based on your symptoms, especially if it’s during peak season. But he may want to give you a quick test to be sure the influenza virus is to blame, and not another health problem.

Why Do You Need It?

When your doctor finds the flu virus, he can give you antiviral drugs early on. This is when they work best. If you get diagnosed early --within 48 hours after symptoms show up -- these drugs can ease your symptoms and shorten the illness by a day or so. After the first 2 days, though, these meds won’t do much for you.

A flu test can also help your doctor rule out giving you antibiotics. Those don’t work against viral infections like the flu.

How Does the Test Work?

Your doctor will rub a swab -- just like the cotton swabs in your bathroom, but longer -- along the back of your throat or up your nose. He’ll seal it in a packet and run a quick test on it himself, or send it out to a lab.

How Long Does It Take to Get Results?

If your doctor does the test himself, or they do it in the lab at his office, the answer usually comes back within 15 minutes.

What Does a Test Look For?

It's checking for the virus. Some tests can help your doctor figure out which flu virus you have, influenza A or B.

Are All Tests the Same?

No. The quality of the test depends on the maker, how the test works, and how big a sample of the virus your doctor can collect.

WebMD Medical Reference

Reviewed by Jennifer Robinson, MD on January 20, 2015
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