The itchy lower body after sex may be related to excessive friction, cross-infection, vaginal inflammation and so on. 1. Excessive friction: In the process of sexual life, if the action is too intense, the amplitude of the action is too large, may cause repeated friction on the vaginal wall of the woman, resulting in vaginal wall congestion, edema, and then itchy symptoms. 2. Cross-infection: some men or women themselves suffer from infectious diseases, such as: vaginitis, glans, etc., in the same room without wearing a condom, it is easy to lead to pathogenic bacteria invasion caused by cross-infection, so in the sex after the itchy lower body symptoms. 3. Vaginal inflammation: some women suffer from trichomonas vaginitis, bacterial vaginitis, vulvovaginal pseudomycosis and other vaginal inflammation, in the process of sex, may lead to infection, vulvar itching symptoms further aggravate. In addition to the above reasons, allergy to condoms, allergy to semen, glansitis and other reasons may also lead to the symptoms of itchy lower body after having sex. If the symptoms of itchy lower body after sex occur frequently, it is recommended to go to the hospital in a timely manner, to clarify the cause of the disease, and then under the guidance of the doctor for the cause of the treatment.