We’ve gotten to the point in the COVID-19 pandemic where you’re probably not stressed every single day about getting the virus—the wide availability of COVID-19 vaccines and effective treatments have thankfully made that possible. And, with that, you likely have some tests around your place for the just-in-case that may have been sitting there for a while. Here’s the thing, though: They can expire. Yep, there is a COVID test expiration date printed on your package that you may not even realize is there.
Many COVID-19 tests last for just a year or so, but the odds are high that you’ll need to use yours at some point. That may or may not be before the expiration date stamped on your package passes. So, do expired COVID tests work, or do you need to toss what you thought was a perfectly good test? It’s actually a little complicated. Here’s what you need to know.
So, do expired COVID tests work?
Yes and no. To fully understand that, it’s important to explain how COVID-19 tests get an expiration date in the first place. “When tests are developed, the company will assess the test over time to make sure it’s performing with the quality standards intended,” says Thomas Russo, M.D., a professor and the chief of infectious diseases at the University at Buffalo in New York. “Whatever time frame they assess it for is the expiration date that will go on that test.”
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This “doesn’t necessarily mean that the test won’t perform for a longer period of time,” Russo says—it’s just the amount of time that the test has been assessed for and what is authorized or approved by the Food and Drug Administration (FDA).
Older tests are more likely to have shorter expiration dates because there were time pressures to get tests out earlier in the pandemic, when they were first developed, and only so much time since they had been created to test how long they were good for, Russo says. “However, companies kept assessing the tests over time,” he says.
As a result, “many manufacturers have received shelf life extensions by the FDA,” says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security.
The FDA has a list online of authorized home COVID-19 tests, along with links to “updated expiration dates” so you can check to see if your test’s expiration date has been extended.
“If you have a test and it’s ‘expired’ based on what the package says, it may or may not be the most correct expiration date,” Russo says.
What happens if you use an expired test?
Again, the expiration dates are a reflection of how long the company that manufactured the test found that it was good for—or the period of time in which they were able to assess the test. With that, there’s a chance that your test will still be good beyond the expiration date listed. “Most tests will still perform past their expiration date for several weeks,” Adalja says.
If the test has truly expired “you are more likely to get a false negative,” says Jamie Alan, Ph.D., associate professor of pharmacology and toxicology at Michigan State University. “The test might be negative because the reagents or ‘ingredients’ are past their shelf life and are not working as they should,” she explains. “They are likely good past their expiration date, although how long I cannot say with any degree of certainty.”
If you have symptoms of COVID-19 and the only test you have at home is expired, Alan says you could try it. “If you get a positive, you are probably positive,” she says. “If you get a negative, it would be good to follow up with another test, either a PCR test or another rapid at-home test.”
Why do COVID tests expire?
COVID tests contain specific reagents (a.k.a. ingredients) that react with the virus, or lack thereof, from your swab, Alan explains. “These ingredients do not work forever,” she says. “This is true for medications, lab materials, and food.”
How do I know if my BinaxNOW is expired?
BinaxNOW is one of the most popular home tests out there, and it typically has an expiration date stamped on the back of the box. But, again, that may not be the most up-to-date expiration date for your test.
If you have a test with an expired date on the package, check out the FDA’s list of updated expiration dates for BinaxNOW tests to see if it’s been extended. Just keep in mind that you’ll need to have your box’s lot number handy.
But, if your test is expired—both on the box and per the FDA’s updated dating—and you want to be sure you’re getting an accurate reading, Russo says it’s “probably best to not use that test.”
This article is accurate as of press time. However, as the COVID-19 pandemic rapidly evolves and the scientific community’s understanding of the novel coronavirus develops, some of the information may have changed since it was last updated. While we aim to keep all of our stories up to date, please visit online resources provided by the CDC, WHO, and your local public health department to stay informed on the latest news. Always talk to your doctor for professional medical advice.
