The reasons why you can’t wash your hair during menstruation are considered to be the following: First, it is easy to cause menstrual cramps because washing your hair can have a strong stimulation on your scalp. Washing hair during menstruation, even with hot water, but the head can not guarantee that it is always in the water, at this time if the invasion of wind and cold, there is a strong stimulation of the nerves of the scalp, and there is indirect stimulation of the uterus, which can cause contractions. If this happens for a long time, it may cause dysmenorrhea. Second, increase the probability of migraine. Some women can experience migraines during their menstrual period. If you wash your hair at this time, it is easy to increase the probability of wind and cold attacking your head, which can lead to migraines more easily. Third, it can lead to infertility. If you wash your hair during your period, it is easy to cause the phenomenon of uterine cold. The uterine cold can not only cause dysmenorrhea or menstrual disorders, in serious cases, may cause premature amenorrhea phenomenon, can bring the risk of infertility to women of childbearing age. Once a woman is amenorrheic, she will not ovulate again and thus can become infertile. Therefore, women should not wash their hair as much as possible during their periods, at least not during the first 3 days of their periods.