With at-home COVID tests now readily available, some might be saving there's for when they have a need to test, but how long can you actually wait?
According to the U.S. Food and Drug Administration, the tests, including ones sent to Americans for free by the government, can expire.
"COVID-19 tests and parts they are made of may degrade, or break down, over time," the FDA states on its website. "Because of this, expired test kits could give inaccurate test results."
How long the tests last will depend on the maker.
The FDA late last month extended the shelf life for iHealth's rapid at-home tests to nine months. This brand of test was among those distributed for free by the government.
The catch? The tests need to be stored at between 2 and 30 degrees Celsius, or between 35 and 86 degrees Farenheit.
Similarly, in January, the FDA extended the shelf life for BinaxNOW tests to 15 months - for tests stored at room temperature.
Full coverage of the COVID-19 outbreak and how it impacts you
Typically the FDA states COVID tests expire between four to six months from the time the test was manufactured.
"COVID-19 test manufacturers perform studies to show how long after manufacturing COVID-19 tests perform as accurately as the day the test was manufactured," the FDA reports. "Since it takes time for test manufacturers to perform stability testing, the FDA typically authorizes at-home COVID-19 tests with an expiration date of about four to six months from the day the test was manufactured, based on initial study results."
But once additional studies are complete, manufacturers can apply for extended expirations.
"Once the test manufacturer has more stability testing results, such as 12 or 18 months, the test manufacturer can contact the FDA to request that the FDA authorize a longer expiration date," as seen with iHealth, according to the agency.
The FDA said it does not recommend using a test after the listed expiration date.