Normal menstruation lasts about 30 days, and between 21-35 days is normal. A woman’s menstrual cycle is influenced by the estrogen and progesterone secreted by the ovaries, and sometimes by mental and psychological factors, environmental factors, work pressure, etc., and it is normal for it to be one week earlier or later. The menstrual period is within 3-7 days, the volume of menstruation is within 20-70 milliliters, the menstrual blood is dark red, and there is no dysmenorrhea. If a woman has dysmenorrhea, it is mostly due to the tight cervical opening, uterine cold, stagnation of qi and blood stasis, or the presence of endometriosis. Women need to give appropriate symptomatic treatment, keep warm during menstruation, do not eat cold, spicy food, and maintain a relaxed mood.