Can You Still Use an Expired COVID Test?

If you have old COVID tests in your medicine cabinet, it may be tempting to use one. However, COVID tests do expire and may not be accurate after the expiration date. Some tests may still be reliable right around or just after the expiration date printed on the test.

COVID tests will stop working over time and can't be counted on to give a correct diagnosis past the expiration date, Ryan Relich, PhD, medical director of the division of clinical microbiology at Indiana University Health, told Health. But the rapid test's true expiration date may not be the one printed on the side of the box.

Here's what to know about expiration dates on COVID rapid tests and when you may be able to still use one that appears expired on the box.

Determining the True COVID Test Expiration Date

When COVID-specific rapid antigen tests were first approved, they hadn't been around long enough for manufacturers to study their long-term shelf life, according to Sanjat Kanjilal, MD, MPH, associate medical director of clinical microbiology at the Brigham & Women's Hospital in Boston and instructor at Harvard University. 

Because of that, test manufacturers and the Food and Drug Administration (FDA)—the agency in charge of approving and monitoring such health devices—erred on the safe side. Those initial expiration dates are printed on the outer packaging of tests.

However, the tests have been around long enough to measure their accuracy over time, and the FDA continues collecting data about their true shelf lives. A test's shelf life is how long it is expected to perform effectively.

The FDA usually sets COVID-19 test expiration dates for 4-6 months after manufacturing. If stability tests performed by the manufacturer show that a test has a shelf-life greater than six months, the FDA might approve extensions of that test's expiration date.

Do Expired COVID Tests Work?

Check the expiration date before using a COVID rapid test. If the test is past its shelf-life, look on the FDA website to determine if its shelf-life has been extended. The FDA has compiled a list of dozens of different at-home COVID tests along with their most accurate and up-to-date expiration dates.

The FDA is the final word on whether a rapid test is still OK to use.

That's when you can use what appears to be an expired rapid test—if the FDA has extended its expiration date, according to Relich.

Are Expired COVID Tests Accurate?

COVID rapid tests typically contain two components subject to expiration: vials of liquid and testing strips.

When the vial liquid comes into contact with SARS-CoV-2, it prompts the virus to release its antigen proteins. The test strip contains SARS-CoV-2-antigen-specific antibodies, which have been conjugated with luminescent indicators. When the antigen proteins come into contact with the antigen-specific antibodies, an additional colored line appears on the test, indicating a positive result.

Over time, those components of the rapid tests can break down, making the test less sensitive and less reliable. The degradation of these tests is why results from expired antigen tests shouldn't be wholly trusted.

"If the antibodies or antigens printed on the rapid test have degraded, it could lead to a higher likelihood that the proteins in the patient sample fail to bind, and that leads to false negatives," said Dr. Kanjilal. 

However, newer research suggests that some tests might be just as effective months after the believed expiration date.

Can an Expired Test Give a False Positive?

The most important factor is the probability a person was infected with COVID before taking the test. A positive test is more believable if you have symptoms or had known close contact with someone who had or has COVID-19.

That doesn’t mean you’re in the clear if you have no known exposure. Center for Disease Control (CDC) COVID-19 tracking data shows that cases continue to fluctuate, and some newer mutations are more contagious.  

Follow up with a PCR if you have a positive at-home test but no symptoms and no known COVID exposure. If you have symptoms but have a negative at-home test, confirm the result with a PCR, which is more accurate but can take a few days to produce results.

What To Do With Expired COVID Tests

If you have expired tests at home that have not had their expiration date extended, you can dispose of them in your normal trash and replace them with new ones. Try to dispose of them in a way that prevents anyone from accessing them, as they can cause harm if used incorrectly.

A Quick Review

If you can avoid it, don’t use an expired test at all. Instead, go right for a fresh rapid test or PCR. There are already many variables that contribute to when and if a person tests positive for COVID, and an expired test adds even more uncertainty.

This is the current information on the FDA and Centers for Disease Control and Prevention (CDC) websites, but research continues to change. Refer to the FDA and CDC websites for the most up-to-date information.