The generic name of Mannitol is Levonorgestrel IUD System, and wearing Levonorgestrel IUD System with black blood may or may not be normal. The levonorgestrel IUD system is mainly used for contraception and treatment of excessive menstruation. Common adverse reactions after placement include irregular vaginal bleeding, including increased or decreased menstrual bleeding, spotting, which can be black, brown, or coffee-colored, and scanty or amenorrheic menstruation, which is mostly normal for the first 3 months after placement. The above adverse reactions often gradually decrease or even disappear 3 months after the implantation. If they are not relieved or even aggravated 3 months after the implantation, it is necessary to recommend timely hospital consultation to rule out abnormalities such as subluxation of the device or cervical lesions. It is contraindicated in cases of liver impairment, known or suspected pregnancy, inflammation of the reproductive tract, abnormal cervical development, progesterone-dependent tumors, and unexplained abnormal uterine bleeding. Consultation with a medical professional is recommended for specific cases.