Do Covid tests expire? (And can you use them anyway?)

Key Points:

• At-home Covid-19 tests do expire. The components in the test can break down over time, leading to inaccurate results.
• The FDA has extended the expiration dates for many at-home tests. It’s a good idea to check the official FDA website before you throw out an expired test.
• If you test positive, there are treatment options available. Antiviral medications like Paxlovid and Molnupiravir can prevent severe illness in at-risk individuals.

At-home Covid tests have been a critical part of controlling the Covid-19 epidemic. These tests are fast, convenient and can be completed at home without any special equipment. They’re so valuable, in fact, that the federal government is again offering four free at-home test kits to all US households.

But what should you do if you reach for an at-home test and realize it’s expired? Not only have Covid tests sometimes been difficult to find, but they can also be pricey. Here’s what you need to know about expired Covid tests, including safety and accuracy.

And if you do test positive? Dr. B can help with that, too. Learn about our same-day Covid-19 consultations and convenient online prescriptions for Covid-19 treatments.

How do at-home Covid-19 tests work?

Most at-home Covid-19 tests are rapid antigen tests. An antigen is any substance that triggers your immune system to respond by making antibodies. Antigens can come from viruses, bacteria, allergens or chemicals.

At-home tests are designed to pick up antigens from the SARS-CoV-2 virus—the virus that causes Covid-19.

Here’s how an at-home Covid-19 test works:

1. Take a sample of mucus using a swab—usually from your nose.
2. Mix the sample with chemicals using a vial or test card.
3. Wait 10-15 minutes. The chemicals will change color if they detect any Covid-19 antigens.

To get the most accurate results, be sure to follow these tips:

• Test during the first week of experiencing symptoms.
• Follow the instructions carefully. 
• Be sure to insert the swab exactly as instructed. If you don’t collect a good sample, there may not be enough of the virus for the test to work correctly.
• Check the expiration date to make sure the test is still valid.

Do Covid tests expire?

At-home Covid tests do expire. But many tests still work after the original expiration date on the box.

When at-home Covid tests first became available, manufacturers were very conservative with the expiration dates. The US Food and Drug Administration (FDA) has extended the expiration dates for many tests. Before you throw out an expired test, check the official FDA website to see if your test’s expiration date has been extended.

It may not work correctly if the test is past its expiration date. That’s because the materials in the test can degrade or break down over time, leading to an invalid test result.

How accurate are Covid-19 tests?

At-home rapid tests are convenient and easy to use. But they aren’t sensitive enough to identify all infections. They work best if there’s a large amount of the virus in your system. So if you’re in the early stages of infection or have started to recover, there may not be enough virus particles for the test to detect.

The accuracy of at-home tests can also vary a lot. The tests work best when someone shows symptoms of Covid-19, like coughing, sore throat, fever and loss of taste or smell. Tests are also more accurate in the first week of illness.

Other research shows that rapid tests may not work as well with newer variants, like Omicron. This could be because symptoms can start sooner with newer variants, so people are testing before viral loads are high enough to trigger a positive test.

Accuracy also depends on whether you perform the test correctly. Getting a good sample can be tricky since you have to insert the swab far enough and long enough into the nasal passages to pick up a good sample. If you don’t get a good sample, the test may not work.

Can Covid tests give a false negative?

A false negative is when someone does have Covid, but the test is negative. Unfortunately, at-home Covid tests can give false negative results.

At-home tests are about 73% accurate.) when used in people with symptoms. This means that the test will be positive in three out of four people who are sick. Another one out of four people will have Covid but test negative.

The accuracy rate increases to 82% if the test is used in the first week of symptoms. This is when the viral load (the amount of virus in your system) tends to be highest.

The test is only about 55% accurate if a person shows no symptoms—so the test will only detect Covid correctly about half the time. The other half of people with no symptoms will have Covid but test negative.

Can Covid tests give a false positive?

False positives are when the test is positive, but you don’t actually have the infection. This is not common with at-home tests. But as we’ve detailed above, if you take a rapid at-home test and get a positive result, you almost definitely have the infection.

Which Covid test is best?

There are more than 30 at-home rapid tests available today. Rapid at-home tests generally work the same way and have similar accuracy rates.

You can purchase rapid tests over-the-counter at pharmacies or online. As of November 2023, you can still get a limited number of free tests from the government.

The most accurate tests are PCR tests. PCR tests use a different kind of technology, so they may take longer to get results. They can also be more expensive—but they’re highly accurate. These tests usually need to be done in a medical provider’s office.

My Covid test was negative! What now?

Just because your at-home rapid test was negative doesn’t mean you’re in the clear. A negative test result could mean:

• You are not infected with the Covid-19 virus
• You tested too early (less than five days since exposure)
• You tested too late (you’re already starting to recover)
• You have a very mild case
• You didn’t get a good sample from inside your nose
• The test was performed incorrectly
• The test was damaged or expired
• You have a variant that the test doesn’t detect very well

The bottom line? If you have symptoms like cough, fever or loss of taste and smell, it’s best to assume you’re sick. Stay home, avoid contact with others and rest until you feel better.

Need to know for sure if you have Covid-19? Take a test every 48 hours up to three times, or follow up with a PCR test. Ask your pharmacist or medical provider if you have any questions or concerns about your test results.

My Covid test was positive! What now?

If you test positive using an at-home rapid test, there’s no reason to panic. Most people can recover at home with few complications.

Some people are still at high risk of becoming very sick with Covid-19. This includes older adults (over age 50), the very young and people with compromised immune systems or other medical conditions (like heart disease or diabetes). Such at-risk individuals may benefit from Covid-19 treatments like Paxlovid or Molnupiravir, which you can only get from a licensed medical provider.

It’s important to start antiviral Covid-19 treatment within five days of your first symptoms. So if you’re sick and want to skip the waiting room, come to Dr. B for a convenient online Covid-19 consultation. Take a short health survey to connect with a licensed medical provider who can help you understand your treatment options. If applicable, they’ll call a prescription into your chosen pharmacy within just a few hours.

Sources:

A.D.A.M. Medical Encyclopedia. Johns Creek (GA): Ebix, Inc., A.D.A.M.; (2023). Antigen.

Centers for Disease Control and Prevention. (2022). Covid-19 risks and information for older adults.

Centers for Disease Control and Prevention. (2023). COVID-19 testing: what you need to know.

Cochrane Library. (2022). How accurate are rapid antigen tests for diagnosing Covid-19?

Rao, A., et. al. (2023). Sensitivity of rapid antigen tests against SARS-CoV-2 Omicron and Delta variants. Journal of Clinical Microbiology.

US Food and Drug Administration. (2023). At-home Covid-19 diagnostic tests: frequently asked questions.