Why Was My Rapid Flu Test Negative?

You may be suffering from classic flu symptoms of body aches, fever, cough, and headache. But when you go to your healthcare provider to be tested, the initial results come back negative. There are a couple of reasons this might occur. The in-office rapid flu test may show a false negative or you may have a flu-like illness that is not influenza.

rapid flu test results
Illustration by Brianna Gilmartin, Verywell

False Negative

The rapid flu tests that most healthcare providers use are a great tool, but they can be wrong. Accuracy can range anywhere from 50 to 90 percent, depending on the test and prevalence of the flu in the community.

A "false negative" result means you had influenza but the test did not detect it.

A "false positive" result means it detected influenza but you didn't have influenza.

False negatives are more likely when flu activity is high, but can occur at any time. Similarly, false positives are more common when flu activity is low. Factors such as how long you've been sick, the type of specimen that was taken (typically a nasal or throat swab), and the type of influenza virus can affect the outcome of the rapid flu test.

More accurate tests can be performed by specialized labs, but these are rarely collected in the general public just to make a diagnosis. Most often, these tests are performed, and results are then sent to the U.S. Centers for Disease Control and Protection (CDC) to keep tabs on circulating influenza strains and the rate of flu activity throughout the country.

If your healthcare provider suspects your flu test was a false negative, they may still diagnose you and treat you for influenza. The rapid flu tests are available to health care providers as an additional tool but are not the only deciding factor.

It's Not Influenza

Influenza isn't the only virus out there that causes more severe symptoms than a cold. Viruses such as adenovirus, parainfluenza, and respiratory syncytial virus (RSV) can cause all of the miserable flu symptoms, but do not respond to antiviral medications that are effective against influenza.

While these viruses can certainly leave you feeling awful for a few days, they are less likely to lead to serious complications, secondary infections, or death as influenza.

If you are diagnosed with a flu-like illness instead of influenza, your treatment may differ slightly, but many of the same over-the-counter medications may be effective.

A Word From Verywell

Whatever the reason for your negative flu test, make sure you understand your diagnosis and treatment options. Your healthcare provider can recommend prescription and over-the-counter medications that can help you feel better faster.

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Article Sources

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  1. U.S. Centers for Disease Control and Protection. Rapid Influenza Diagnostic Tests.

  2. Epperson S, Davis CT, Brammer L, et al. Update: Influenza Activity - United States and Worldwide, May 19-September 28, 2019, and Composition of the 2020 Southern Hemisphere Influenza Vaccine. MMWR Morb Mortal Wkly Rep. 2019;68(40):880-884. doi:10.15585/mmwr.mm6840a3.

  3. U.S. Centers for Disease Control and Prevention. Diagnosing the Flu.