If the vulva is itchy after every coitus, the most common cause is semen allergy, which can lead to localized redness and swelling of the vaginal mucosa. The most common clinical cause is semen allergy, due to women’s allergic reaction to semen, so clinically it will lead to localized redness and swelling of the vaginal mucosa, more serious itching, it is recommended that anti-allergy treatment. In addition, clinically appear after coitus vulvar itching, may also be due to local inflammation of the vagina, such as mycoplasma infection, chlamydia infection, candida vaginitis, trichomonas vaginitis or bacterial vaginosis; in the coitus, the outside world stimulation can also cause local itching, it is recommended to combine with the clinical history, such as leukorrhea is more, it is recommended to do a high power microscope leucorrhoea routine laboratory tests, according to the infected pathogenic bacteria, and then give the appropriate treatment. According to the pathogenic bacteria, then give the appropriate drugs for treatment.