Flu Tests: Who Should Test and When?

An illustration of a gloved hand holding a nasal swab up to a person with long brown hair and a red shirt on a blue background.


Key Takeaways

  • There are many options available to test for the flu, including rapid tests that can give you results in minutes. 
  • Flu tests are only recommended for people who are showing flu-like symptoms such as fever, sore throat, coughing, or sneezing. 
  • If you have signs and symptoms of the flu, test as soon as possible so you can get treated and avoid others to prevent them from getting sick.

Testing for infectious illnesses became a new holiday tradition thanks to COVID-19. This year, other respiratory viruses are making a comeback, and many people are wondering if they can (and should) test for them before gathering with loved ones.

With all these viruses crashing the party, it can be hard to tell which one you’re dealing with. They might even show up wearing the same outfit, as respiratory illnesses can share symptoms like a fever, cough, sore throat, runny nose, and headache.

One unwelcome guest at holiday celebrations this winter is the flu. According to the Centers for Disease Control and Prevention (CDC), current counts of positive flu tests and flu hospitalizations are the highest in over a decade. So far this season, there have been at least 15 million illnesses, 150,000 hospitalizations, and 9,300 deaths from the flu.

Not only are the flu and COVID going around at the same time, but they can give you many of the same symptoms. The only way to know for sure what’s making you sick is to get tested.

You might have a stockpile of COVID tests at home and know how to use them—but what about testing for the flu?

Here’s what you need to know about flu testing options, including how to tell if you need to get tested, when you should test, and how long you’ll have to wait to get results.

What Are My Flu Testing Options?

Having flu-like symptoms can be a clue that you have the flu, but symptoms alone are not enough to know for sure. You can have flu-like symptoms that are less common, symptoms that fall outside of the typical flu season, or even symptoms that are similar to other respiratory illnesses like COVID or a cold.

Greg Schrank, MD, an associate hospital epidemiologist at the University of Maryland Medical Center and assistant professor of medicine at the University of Maryland School of Medicine, told Verywell that getting a flu test is the only way to know for sure whether or not you or a loved one has the flu.

“Diagnosis of the flu can be made presumptively based on symptoms—especially in a person with a known close exposure to a confirmed case, such as someone who lives at home with them,” said Schrank. “However, testing of the respiratory tract is the only way to confirm the diagnosis.”

Diego Hijano, MD, MSc, an infectious disease expert at St. Jude Children’s Research Hospital, told Verywell that there are different kinds of flu tests that can be done quickly. They usually involve inserting a swab into your nose or throat.

Rapid Influenza Diagnostic Tests (RIDTs) 

One of the most common flu tests is RIDTs (flu antigen tests). According to Hijano, these tests work by detecting parts of the virus that trigger an immune response, called antigens. These tests can also identify the presence of influenza A and B.

Hijano said that for RIDTs, a swab is inserted into your nostril to get a sample—a similar process to how rapid antigen COVID tests work. RIDTs can give a result within 10 to 15 minutes, but the results are not necessarily as accurate as other flu tests.

Rapid Molecular Assay Tests

Kevin Ban, MD, chief medical officer for Walgreens, told Verywell that rapid molecular assays are another type of flu test that can detect the genetic material of the flu virus.

While these tests can also produce results within 15 to 20 minutes, Ban said they are known to be more accurate than RIDTs. According to the CDC, rapid molecular assays can detect influenza virus in the upper respiratory tract with high sensitivity and about 90 to 95% specificity.

According to Ban, rapid molecular assay tests also require a sample of fluid either from your nose or throat which is typically collected with a swab.

Other Lab Tests 

In addition to RIDTs and rapid molecular assays, Ban said there are other flu testing options like polymerase chain reaction (PCR) and viral culture tests that are more in-depth and accurate. These are often done in specialized settings like hospitals, clinics, and public health laboratories. 

Just like the other options, these tests require a healthcare provider to collect a sample from your nose or throat using a swab, which is then sent to a lab for testing. However, patients may not get results for several hours or even days.

Hijano said that all flu tests are done at a provider’s office—however, there are some options that pharmacies can offer. For example, Walgreens currently offers rapid molecular assay testing for the flu where results come back within two hours.

According to Schrank, there are currently no over-the-counter (OTC) flu tests that can be purchased for use at home. However, there are some tests that can check for flu, COVID, and respiratory syncytial virus (RSV). People who use these tests will collect their own samples and send them to a lab company to be processed.

Hijano said that it can take up to two days or longer to get results with these options, so they’re not as convenient as other available options.

Who Should Get Tested For The Flu?

According to Hijano, flu tests are only recommended for people who are showing symptoms such as fever, sore throat, coughing, and sneezing. Getting a confirmed diagnosis of the flu can help patients and their providers move ahead with treatment options.

Diego Hijano, MD, MSc

Getting tested has become sort of a common practice for COVID, but for flu, I wouldn’t recommend people just going out and getting tested if they don’t have any symptoms at all.

— Diego Hijano, MD, MSc

“Getting tested has become sort of a common practice for COVID, but for flu, I wouldn’t recommend people just going out and getting tested if they don’t have any symptoms at all,” said Hijano. “But if you have symptoms—even if they are mild—getting a test can help ensure that you don’t gather with family and friends and can inform your medical care.”

Schrank added people who are at risk for severe flu infection, such as older adults, people living with chronic medical conditions like lung or heart disease, or people with compromised immune systems should also consider getting evaluated and tested for the flu.

When Should I Take A Flu Test? 

Barbara Bawer, MD, a family medicine physician at The Ohio State University Wexner Medical Center, told Verywell that if you're going to test for the flu, you should do it as soon as you develop symptoms—especially considering symptoms of the flu and COVID overlap.

“It is very important to get tested if you are having symptoms so that you know what you have, can get treated appropriately, and avoid spreading it as well,” said Bawer.

Ideally, Ban said that testing should be done within the first three days of symptom onset, mainly if you were exposed to someone with the flu within the last three days or are at high risk of developing complications from the flu.

What Should I Do If I Get a Positive Flu Test?

If you take a flu test and your result is positive, Schrank said your healthcare provider will go over treatment with you. You should also ask your provider questions, like if you will need to remain in isolation, how long you will need to rest, and how long you will need to stay home from work or school.

“Talking with your primary care doctor can be helpful to understand the options for testing and treatment if needed—especially if you are at high risk of severe disease from these respiratory viruses,” said Schrank.

On the other hand, if you test negative for the flu, your provider can also guide you on what to do next. For example, if you haven’t already, they might test you for COVID.

How Can I Avoid the Flu?

Health is a gift you can give yourself all year round, not just during the winter months. To keep you and your loved ones safe from the flu, COVID, and other illnesses this holiday season, experts say that you should:

What This Means For You

There are many testing options for the flu, however, experts only recommended testing if you’re showing symptoms of flu-like illness. Call your healthcare provider to get a test and find out what you should do next, depending on your results.

7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. The difference between flu and COVID-19.

  2. Centers for Disease Control and Prevention. Weekly U.S. influenza surveillance report (FluView).

  3. Centers for Disease Control and Prevention. Flu symptoms & diagnosis.

  4. Centers for Disease Control and Prevention. Diagnosing flu: questions & answers.

  5. Centers for Disease Control and Prevention. Overview of influenza testing methods.

  6. Walgreens. Walgreens now offering flu and COVID-19 testing in a single visit at over 5,000 locations.

  7. Centers for Disease Control and Prevention. CDC’s influenza SARS-CoV-2 multiplex assay.

By Alyssa Hui
Alyssa Hui is a St. Louis-based health and science news writer. She was the 2020 recipient of the Midwest Broadcast Journalists Association Jack Shelley Award.