How to Check the Expiration Date on a COVID Test

Every at-home COVID test has an expiration date printed on its box, but that printed date is often not the real deadline. The FDA granted shelf-life extensions to dozens of rapid antigen tests during and after the pandemic, meaning the test sitting in your bathroom cabinet may still be valid even if the box says otherwise. Finding the actual expiration date takes two steps: reading what is on the packaging and then cross-referencing it with the FDA’s updated list of authorized extensions. Here is how to do both, plus what you should know about whether an expired test is worth using at all.

Where to Find the Printed Expiration Date

Most at-home COVID rapid antigen tests print the expiration date on the outside of the cardboard box, usually on a side panel or on the back near the lot number. It is typically labeled “EXP,” “Use By,” or “Expiration Date” and formatted as a month and year (for example, 2024-06 or 06/2024). Some brands also stamp the date on the sealed foil pouch inside the box. If you have thrown away the outer carton, check the foil wrapper before assuming the date is lost.

The lot number printed near the expiration date matters just as much as the date itself. It is the key you will use to look up whether the FDA extended your particular test’s shelf life. Lot numbers are alphanumeric strings and are usually right next to or directly above the expiration date. Write it down or take a photo before you recycle the box.

How FDA Expiration Extensions Work

When COVID test manufacturers first applied for emergency use authorization, they could only prove shelf stability for a limited window, sometimes as short as a few months, because real-time aging data did not yet exist. As time passed and manufacturers ran longer stability studies, they submitted evidence to the FDA that their tests remained accurate well beyond the original printed date. The FDA then authorized new, longer shelf lives for specific lots.

The result is that many tests carry a printed expiration date that is significantly shorter than the date the FDA now considers valid. The FDA maintains a publicly accessible webpage titled “At-Home OTC COVID-19 Diagnostic Tests” that lists every authorized test along with its current authorized shelf life. To check whether your test got an extension, go to that FDA page, find your test brand, and look for a link to the manufacturer’s updated expiration-date information. Many manufacturers, including Abbott (BinaxNOW), iHealth, and Quidel (QuickVue), host their own lookup tools where you enter your lot number and get a revised expiration date.

Some tests received multiple rounds of extensions. A BinaxNOW kit originally stamped with a 9-month shelf life, for instance, was later extended to 15 months and then again to 24 months from the date of manufacture. If you last checked your test’s status a year ago and it was expired then, it may have since received another extension that puts it back in range. It is worth checking again before you throw it out.

What If Your Test Is Truly Past Its Extended Date

Even after accounting for all FDA extensions, plenty of people have tests that are genuinely past their authorized shelf life. The question everyone asks next is whether those tests still work. The short answer: probably yes, but with some caveats.

A lab study tested 200 BinaxNOW rapid antigen kits that were 27 months past their manufacture date and about 5 months beyond their FDA-extended expiration. The researchers challenged the tests with live SARS-CoV-2 virus at low and moderate concentrations. At the lower concentration, both expired and unexpired tests detected the virus with identical accuracy. At a moderate concentration, expired tests caught 99 out of 100 positives compared with 100 out of 100 for unexpired tests, a difference so small it was not statistically meaningful.¹ A separate analysis using manufacturer-provided control samples found no change in sensitivity or specificity for BinaxNOW kits tested four months past the manufacturer-extended expiration.²

So a moderately expired rapid antigen test appears to retain most of its ability to detect the virus. That said, these studies looked at one specific brand (BinaxNOW) and a limited window past expiration. The results are reassuring but do not guarantee that every brand or every test five years past its date will perform the same way.

Expect Fainter Lines on Older Tests

One consistent finding in research on expired tests is that the positive lines are visibly fainter than what you would see on a fresh kit. In the BinaxNOW study described above, expired tests at low viral concentrations produced lines that were described as “only just visible.”¹ The test still registered as positive, but the signal was weaker.

This matters in real life because a faint line is harder to interpret. If you are using an older test and see a very light second line, treat it as a positive. Any visible color in the test region, no matter how pale, counts. The concern is not that a faint line is ambiguous in meaning; it is that someone might dismiss it as a shadow or an artifact. Take a photo of the result window in good lighting to examine it closely. If you are uncertain, repeat the test with a second kit if one is available.

Storage Conditions Matter More Than the Calendar

The expiration date on your test assumes it was stored under specific conditions, typically room temperature and dry. How and where the test spent its life has a meaningful impact on whether it still works, sometimes more than whether the date has passed.

Heat is the bigger enemy. A study of eleven different rapid antigen tests found that storing them at body temperature (around 37°C or 99°F) for three weeks caused about a tenfold drop in sensitivity for the majority of brands tested.³ That is roughly the temperature inside a car on a warm day or a garage in summer. Even running the test itself at elevated temperatures, with just ten minutes of warm-up before use, reduced sensitivity for nearly half the brands tested. The practical takeaway: a test that sat in a hot mailbox for a few hours during delivery is one thing, but a test that lived in your car’s glovebox all summer may have degraded regardless of whether it is within its printed shelf life.

Cold is a different problem. The same study found that running tests at temperatures near 2–4°C (refrigerator cold) caused false-positive results on two of the six brands evaluated for that scenario.³ If your test has been stored in a cold place, like an unheated garage in winter, let it come to room temperature before you open the foil pouch and run the test. Most package inserts recommend waiting at least 15 to 30 minutes.

Brief exposure to extreme temperatures during shipping, on the other hand, appears to be less of a concern. A study of the Ellume COVID-19 At-Home Test found that exposure to extreme heat and cold for up to two weeks did not affect the test’s ability to correctly identify positive and negative samples.⁴ So a package that sat on your porch in the cold for a day or two after delivery is likely fine, but long-term storage in an uncontrolled environment is a different story.

Why the Desiccant Packet Inside the Pouch Is Not Just Filler

When you open a COVID test kit, you will usually find a small silica gel packet tucked inside the sealed foil pouch alongside the test strip or cassette. That desiccant exists to keep moisture away from the test’s reactive components. Lateral flow tests, the technology behind most rapid antigen COVID tests, rely on antibodies and other proteins that are dried onto a membrane strip. If moisture creeps in, those proteins can degrade or the test strip can activate prematurely.

This is one reason the instructions tell you not to open the foil pouch until you are ready to test. Once the pouch is opened, the desiccant can no longer protect the strip from ambient humidity. If you opened a test months ago, peeked at it, and then sealed it back in a plastic bag “for later,” there is no guarantee it still works. The seal matters. An unopened foil pouch stored at room temperature is far more trustworthy than one that was opened and resealed, even if the latter is technically within its expiration date.

Rapid Antigen Tests Versus Molecular At-Home Tests

Most COVID tests that people have stashed at home are lateral flow rapid antigen tests, like BinaxNOW, iHealth, and QuickVue. These detect viral proteins and give results in about 15 minutes. Their shelf life, as discussed, is typically in the range of one to two years, sometimes longer with FDA extensions.

A smaller number of at-home molecular tests also exist. These detect viral genetic material (RNA) and tend to be more sensitive than antigen tests, but their shelf-life story is different. The chemical reagents used in molecular detection, particularly the enzymes, are generally less stable than the antibodies in a lateral flow strip. One lab-developed molecular home test using a freeze-dried format maintained accuracy for at least 30 days at refrigerator temperature and about 10 days at room temperature.⁵ That is dramatically shorter than the shelf life of a lateral flow antigen test. If you happen to have a molecular home test (Lucira and Cue were the best-known consumer brands, though availability has shifted), pay even closer attention to the expiration date and storage instructions, because the margin for error is narrower.

If You Are Worried About Accuracy, Test Twice

Whether your test is expired, borderline, or fresh out of the box, the single most effective way to improve a rapid antigen test’s reliability is to test more than once. Research comparing single versus serial testing found that two tests spaced 48 hours apart achieved a peak sensitivity of about 85%, compared with roughly 77% for a single test. Two tests on consecutive days landed in between at around 81%.⁶ The improvement was most pronounced in the first three days after symptoms started, which is exactly when you most want to know your status.

A separate study comparing antigen test performance across different SARS-CoV-2 variants confirmed that serial testing improved sensitivity regardless of which variant was circulating.⁷ So if you are digging a slightly old test out of the medicine cabinet because you feel sick, use two of them a couple of days apart if you have them. The first negative result on any rapid antigen test, fresh or expired, is not as definitive as most people assume.

A Practical Checklist When You Find a Test in Your Drawer

If you have just pulled a COVID test out of storage and you want to know whether it is worth using, here is how to work through it step by step:

Find the lot number: Check the box or the foil pouch for an alphanumeric string near the printed expiration date.
Look up extensions: Go to the FDA’s “At-Home OTC COVID-19 Diagnostic Tests” page and find your brand. Follow the link to the manufacturer’s expiration-date lookup tool and enter your lot number.
Check the foil pouch: If the sealed pouch is intact and has not been opened, the test is more likely to still be reliable. If the pouch was previously opened, consider the test unreliable regardless of date.
Consider storage history: A test stored in a climate-controlled room is in far better shape than one that spent months in a hot car or an unheated shed. Prolonged heat exposure degrades test components even within the expiration window.
Let it warm up: If the test has been in a cold environment, let it sit at room temperature for at least 15 to 30 minutes before opening the pouch and running it.
Read carefully: Older tests may produce faint positive lines. Examine the result window in bright, direct light. Any visible color in the test region is a positive.
Plan for a second test: If you have two kits, use one now and the other 48 hours later for the most reliable result.

When to Skip the Old Test Entirely

There are situations where using a questionable test is not your best move. If you are testing to make a high-stakes decision, such as whether to visit an elderly or immunocompromised family member, the modest risk of a false negative from a degraded test may not be acceptable. In those cases, a PCR test from a clinic or pharmacy provides a much more sensitive result. Similarly, if the foil pouch is damaged, open, or shows visible discoloration of the test strip when you unpack it, do not bother. A test strip that has visibly yellowed or shows patchy discoloration of the membrane has likely been exposed to moisture or heat beyond what it can tolerate.

It is also worth remembering that a negative rapid antigen test, even a perfectly fresh one, does not guarantee you are not infected. These tests are best at detecting the virus when your viral load is high, typically starting a day or two after symptoms begin. Testing too early in an infection is a common reason for false negatives, and that has nothing to do with expiration dates. If you feel sick and test negative, repeating the test in 48 hours matters more than whether the first test was a month past its date.

Why Test Manufacturers Print Conservative Dates

If expired tests often still work, you might wonder why the printed dates are so short in the first place. The answer comes down to how regulatory shelf-life claims work. A manufacturer can only print an expiration date supported by stability data it has already submitted to the FDA. When COVID tests were first authorized under emergency use, companies had only been making them for weeks or months, so the only data available showed stability over that short window. Printing a two-year shelf life would have required two years of data that simply did not exist yet.

As those months and years passed, manufacturers continued testing stored lots and submitted new data showing the products held up far longer than originally labeled. The FDA then issued the extensions that created the gap between what is printed on the box and what is actually authorized. The printed date is not the point at which the test becomes unreliable; it is the point beyond which the manufacturer’s original data package did not extend. That distinction matters when you are deciding whether to use a test or toss it. The date was conservative from day one, and the extensions are the regulatory system catching up with reality.