So says Philip Tierno, professor of microbiology and pathology at New York University.
He says that even after you wash your underwear, there may still be bacteria living on it.
Washing your undergarments doesn’t always totally sanitize them, so you might want to rethink how long you keep them.
Tierno did note, however, that the average person could probably get away with wearing the same pair of underwear two days in row without a problem, though he wouldn’t advise any longer than that.
To be safe, just wear a fresh pair every day.
The best way to wash your undies is in the hot water cycle with bleach, which is the most effective product to kill the organisms living on your undies, Tierno said.
However, some fabrics can’t withstand hot cycles, so cold or warm water with a detergent that contains peroxide is also an option.
In terms of replacing your skivvies, the best practice, according to multiple outlets, is to replace the underwear you wear regularly every year.