Why does underwear change color and can't be washed clean?

The reasons why underwear will change color are:

Some people do not pay attention to the cleanliness of vulva, and secretions are not cleaned up in time.

Some people are embarrassed to put their underwear in front of the door and in the sun, so they have to put it in the shade to dry. Without sunshine disinfection, it is inevitable that some bacteria and molds will breed.

The correct way to wash underwear:

Underwear is best washed by hand. If there are patients with infectious diseases at home, they must also wash clothes separately. After cleaning, soak or wipe the inner tube with disinfectant.

Underwear is generally small. In order to increase the friction density, it is recommended to hold it with your thumb and forefinger and rub it carefully, so as to wash it thoroughly.

Underwear should be changed and washed every day to avoid breeding some bacteria and mold.