A woman’s period of twelve days may be caused by puberty or menopause, endometritis, uterine polyps or uterine fibroids, etc. You can take antiemetic drugs, antibiotic drugs, and some patients need surgery. 1. Puberty or menopause: Puberty women will have menstrual disorders due to immature development of ovarian axis. Menopausal women will also have abnormal menstruation due to the decline of ovarian function and the instability of estrogen. For these two cases, medicines to stop bleeding can be used, such as tranexamic acid and Anluo blood. 2. Endometritis: endometritis is an inflammation of the uterine lining, due to inflammatory stimulation, thickening of the lining can lead to excessive menstruation, prolonged menstruation, this situation requires the use of antibiotic medication, through oral, intramuscular or intravenous drip, etc., the more commonly used drugs are cephalexin, metronidazole, clindamycin, penicillin and so on. 3. Uterine polyps or uterine fibroids: endometrial polyps and uterine fibroids will squeeze the nearby veins, resulting in congestion and expansion of the endometrial venous plexus, causing increased menstrual flow and prolongation of menstrual period, and for these two reasons, the effect of medication is not obvious, and surgical treatment is recommended. All of the above medications should be used under the guidance of a doctor, avoid self-medication.