The hazards of washing hair during menstruation include reduced menstrual flow, shortened menstrual period, and induced or aggravated dysmenorrhea. The bleeding volume on the first 1-2 days of menstruation is relatively high, so washing hair at this time is easy to get cold and may reduce the volume of menstruation and shorten the menstrual cycle. If a woman has symptoms of dysmenorrhea, washing hair during menstruation can easily trigger or aggravate dysmenorrhea. Washing hair during menstruation, although it may have some effect on menstruation if you avoid washing your hair on the first two days of your menstrual cycle, and choose hot water when washing your hair, and dry your hair with a hair dryer or dry towel in time after shampooing, it will not affect your normal menstruation under normal circumstances. You should not dye or perm your hair between menstrual periods, as the body’s resistance is low during menstruation, which can lead to skin allergies.