How to check if your at-home COVID test has expired

Your antigen test may have gotten a new lease on (shelf) life.
expiration date on covid test

Always check that lot number. Sandra Gutierrez

At-home tests have been a critical tool in humanity’s efforts to stop the spread of COVID-19. You may have purchased some at your local drugstore, or ordered them for free through the program the US government launched in January. But they may expire by the time you show symptoms.

The good news is that the Food and Drug Administration—the agency responsible for authorizing COVID tests—is constantly using new data to extend the shelf life of these useful products. This means the ones you have at home may be good for up to 14 months beyond the expiration date on their packaging. All of this information is on the FDA’s website, but you’ll need some guidance to navigate it. 

Check the expiration date of your at-home COVID test

It’s been a couple of days since your friend’s indoor birthday party, and now your throat is sore and your joints are starting to ache. Time for a COVID test.

If the expiration date on your test is long gone, go to the FDA’s list of authorized at-home COVID tests and check the database at the bottom of the page. You can use the search bar by entering your test’s make and model, or you can display all the entries on the list by clicking the dropdown menu on the right and selecting Show all entries. At the time of writing, the FDA has authorized only 22 tests in the US, so displaying the entire list won’t force you to scroll ad nauseam.

[Related: This week is the last chance to order free at-home COVID tests]

Next, find your test. A previous version of this database only had the names of the tests in the first column, but the FDA has since included some visual aids in the form of thumbnails showing the packaging for each test. This makes it easy to see which entry corresponds to what you’ve got at home, and you can scroll down the list until you find the right box. When you do, confirm the make and model of your test match the entry.

On each entry, you’ll find all sorts of useful information for each test, including who can use it, what kind of sample it requires, and how long it takes to get results. The information you’ll need to find out when a COVID test expires is in the last column, all the way to the right, under Expiration date. There, you’ll see the shelf life of the test, and whether it has been extended. If it has, you’ll see the word (extended) right next to it, and a link to a PDF with a list of all the updated expiration dates. 

If your test’s shelf life has been extended, you’ll need to confirm that extension applies to the specific group of tests (the lot) yours comes from. Open the PDF to find a list with three columns: from left to right, you’ll see lot numbers, original expiration dates, and extended expiration dates. To find your test’s lot number, you’ll need to look at the box—you’ll most likely find this six-digit number on the back or one of the sides, usually on a sticker next to the word LOT. 

Go back to the PDF and use your browser’s “find” function to locate the lot number: if you’re using a Mac computer, hit Cmd+F, and if you’re a Windows user, press Ctrl+F at the same time. On the emerging search bar in the top right corner of the browser screen, type in your test’s lot number. Your browser should automatically scroll down to where the number is and highlight it. Note that the original date (middle column) matches the date printed on the box, and then look at the third and last column to see the real expiration date. If that hasn’t passed yet, you’re good to swab away—hopefully, the test comes out negative. 

If your lot number is not on the list, you should abide by the expiration date printed on the box. And if that’s already in the past, the FDA says the test may provide inaccurate or invalid results, so you should throw the test away and get a new one. 

Why the FDA is extending the expiration dates on COVID tests

The expiration date on at-home COVID tests determines how long a test can provide accurate and valid results. Manufacturers choose the date through stability testing, which in this case takes two forms. 

With the first testing method, manufacturers just let a batch of tests sit for a period of time (seven, 13, or 19 months), and then see if the tests still perform as well as they did when they were fresh out of the factory. This method is the most reliable way of ensuring tests work properly, but it’s slow because it requires actual time to pass before manufacturers can, well, test the tests. 

[Related: You can, and should, order more free COVID tests from the US government]

But back at the peak of the COVID-19 pandemic, we couldn’t wait nearly two years to be sure tests were up to standard, so manufacturers used accelerated stability testing. This method consists of storing a batch of tests for a shorter period of time at a high temperature and then checking whether they’re still performing accurately. Tests are made to work ideally between 59 and 86 degrees Fahrenheit (15 and 30 degrees Celsius, approximately). Extreme temperatures can degrade them more rapidly, mimicking the effect that sitting on a shelf for a long time would have. 

This method was useful early on because it allowed the FDA to approve tests and get them into our homes quickly to help us curb the spread. But because accelerated stability testing is not as accurate as just letting time pass, the agency only gave tests a four- to six-month shelf life that could be updated once manufacturers provided more data on stability. 

That is what’s happening right now, and we may continue to see extended expiration dates for at-home COVID tests as more time goes by. For now, though, make sure you check the FDA website before you toss your tests, and take precautions to protect others if you need to go to a public space to get a new test.