If you have your first menstruation at the age of twelve, the estrogen and progesterone secreted are relatively unstable because of the imperfect function of the ovaries, so that the duration of menstruation will be prolonged. If the menstruation has not stopped after twenty days in the clinic, it is recommended that an ultrasound examination can be done to first understand whether the condition of the uterus is normal. If there is no abnormality, it is also recommended to take a blood test for sex hormone six, mainly to understand the endocrine situation, and then give the corresponding medicine for treatment according to the result. The most commonly used medication to stop bleeding in clinical practice, for a girl of twelve years old, is the use of Tonicin, which is recommended to be taken orally to give hemostatic treatment. Since vaginal bleeding is relatively long, the chance of causing infection increases. It is recommended to change sanitary napkins regularly, keep the vulva clean and wash it once a day.