Symptoms of the onset of menstruation include pelvic drop sensation, breast swelling and pain, back pain, headache, irritability, irritability, etc. The degree is relatively mild and does not require special treatment, but some symptoms are more serious and can affect work and life, known as Premenstrual Syndrome (PMS). The onset of menstruation refers to the first day of menstruation. Normal women experience menstruation in cycles, which can last for 3-7 days, and PMS occurs 7-14 days before the onset of menstruation, and the symptoms will disappear or be significantly reduced after the onset of menstruation.