Flu Test: How to Find the Virus

Medically Reviewed by Carmelita Swiner, MD on May 17, 2023
2 min read

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

When your doctor finds the flu virus, they 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.

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. They’ll seal it in a packet and run a quick test on it themselves, or send it out to a lab.

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

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

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.