The reasons for vulvar itching after having sex are as follows: 1, most of them are caused by vulvar inflammation, vaginal inflammation, mycoplasma infection; 2, in some cases, vulvar eczema, allergy, or wearing chemical fiber underwear, tight pants, not paying attention to the hygiene of sex, not paying attention to changing underwear every day, washing the vulva, and paying attention to the hygiene of the vulva, which may also lead to vulvar itching symptoms. Because the hymen will be ruptured after sex, and the hymen has a protective barrier effect, after the hymen is broken, there is a possibility that bacteria or fungi may be retrogradely infected to the uterine cavity through the vagina, or even the pelvis, so there may be vulvar itching, abnormal secretions and other vulvovaginal inflammation or vaginal inflammation symptoms.