The generic name of Mannitol is levonorgestrel intrauterine system, and menstruation refers to menstruation. Levonorgestrel intrauterine system use after a month to the second period is usually due to the drug for menstruation caused by the impact of the drug, is a common adverse drug reactions. Levonorgestrel IUD is a special type of intrauterine device used mainly for contraception and in patients with idiopathic menorrhagia. In the first 3 months after use, most women will have some changes in menstruation, and most of them will have irregular bleeding. Therefore, second menstruation in a month after use is a common adverse reaction, which usually improves after 3 to 6 months. In addition, patients may also experience adverse reactions such as headache, abdominal pain, nausea, and breast pain. It should be noted that it is contraindicated in patients with known or suspected pregnancy, pelvic inflammatory disease, cervicitis, lower genital tract infection, postpartum endometritis, unexplained abnormal uterine bleeding, acute liver disease or liver tumor. Patients are advised to standardize the application under the guidance of a doctor, and should go to the hospital for examination in time if the bleeding is heavy.