Menstruation is the monthly cycle of vaginal bleeding, an important sign of female sexual maturity. 1. Before the onset of menstruation, some women may experience clinical symptoms such as headache, dizziness, nausea, loss of appetite, fatigue, breast tenderness and nipple pain. 2. After the onset of menstruation, the main clinical symptom is bleeding in the vagina. 3. The menstrual blood is dark red blood, which does not clot, and some women may have blood clots in their menstrual blood. 3. Some women may have pain and discomfort in the abdomen and lumbosacral area during menstruation, which is a normal reaction in mild cases, but is a sign of dysmenorrhea in severe cases. 4. After menstruation, women’s body returns to its normal state during non-menstrual periods, and the physical discomfort usually disappears quickly.