December 2022: Whenever you test yourself for COVID at home — whether you’re positive or negative — you should report your result. The results are kept private and anonymous. Every test that gets reported helps public health teams better understand where outbreaks are happening, so they can get help to people who need it.

You just checked your rapid-test package, and the expiration date has passed. Or, maybe your tests arrived in the mailbox on a 95-degree summer day — or on a 12-degree day in January. Yikes! Will they still work? Here’s how to find out.

My rapid tests have expired. 

Good news! If they’ve been kept dry and at room temperature, they’ll probably still work, especially if they expired only recently.

The even better news is that they may not even be expired. Many companies have shown that their rapid tests last longer than was originally anticipated. If you live in California, you’re really in luck: According to your state department of public health, you can use your test no matter what the date on the box says, as long as the control line appears when it’s supposed to (skip to the last paragraph of this article to for an explanation of what that means). If you don’t live in California, your test’s expiration date may still have been extended — by the FDA. The expiration date is usually listed on the back or the side of the package.

Test 1

Test 2

On the Test 1 box above, the date is marked with an hourglass symbol. On the Test 2 box, it’s marked “Use by.”

To find out whether your rapid test's expiration date has been changed, go to the FDA's website and look for the brand of test you have. If you see the word "extended" in the Expiration Date column, then the FDA has changed the expiration dates. Click on the link in that column.

When you get to the next screen, look in the left or middle column for the expiration date that’s printed on the box you have. The date in the right-hand column is the new expiration date for your test.

My rapid tests got very hot / very cold. Will they still work?

Rapid tests are designed to work at room temperature: Between 59 and 86 degrees F / 15 to 30 degrees C. So, if your test got very hot or very cold, make sure you let it cool down or warm up for at least two hours before using it.

If your test froze, that’s not a big deal. Just make sure it has completely thawed and come to room temperature before you use it.

If your test was left in very high temperatures (above 86 degrees F / 30 degrees C) for a long time, it may not work. How long? It’s hard to know for sure, but if it spent more than a day in a scorching-hot mailbox, you might be out of luck.

Once you start a test, one way to know whether it’s working or not is to check if the control line has appeared. (On most tests that’s next to the letter “C,” for “control.”) The control line is there for that exact reason — to make sure the user knows that the test is working. If the line doesn’t appear, then the test didn’t work. But if you’re not sure — especially if your test was stuck in the heat for a long time — play it safe. Open up another box of tests.