If there is a sour smell of underwear after wearing tight pants, but there is no abnormal leukorrhea discharge or vulvar itching, it is a normal physiological manifestation and does not require any treatment. If the sour smell of underwear is accompanied by an increase in leucorrhea, odor and vulvar itching, it is not a normal phenomenon and may be caused by vaginitis. For women who are not sexually active, they still need to have their leukorrhea checked when they have abnormal leukorrhea. If there is no way to apply local medication vaginally after the checkup, you can consider washing your vulva with lotion.