The most common clinical cause of itching down there when you are about to have your period is a pathogenic infection in the vagina. If there is pathogenic bacteria infection in the vagina, this secretion will flow to the vulva and stimulate it, causing itching in the vulva. Therefore, it is advisable to have a routine laboratory test of the leucorrhoea, mainly to find out if there is Candida, Trichomonas, bacterial vaginosis, or mycoplasma and chlamydia infections, and then to give the appropriate clinical treatment according to the infected pathogens. It is also recommended to keep the vulva clean before the menstrual period because of the high discharge. It is best to wash the vulva once a day with 10% cleanser or double ginseng lotion.