If itching of the vulva occurs only occasionally during coitus, it is most likely caused by pathogenic bacterial infection. It is recommended to go to the hospital to do routine tests of the leukorrhea, and then according to the infection of the pathogenic bacteria and then give the appropriate treatment, so that it will not be in the coitus will not appear vulvar itching. If itching occurs every time you have sex, it is likely to be caused by semen allergy. In this case, it is best to use a condom before intercourse to avoid contact between semen and the vaginal mucosa and vulvar skin, which may cause allergy. In addition, it is recommended to do desensitization treatment, go to the hospital can take some oral polyphenols or dexamethasone for treatment, so as not to cause semen and vaginal contact with the allergic phenomenon.