The main reason is that its effect of activating blood circulation and resolving blood stasis may increase menstrual flow, or may lead to shortening of menstrual cycle. Therefore, in case of more serious side effects, such as menstrual flow exceeding 80mL, you can change to other medications for corresponding treatment to avoid long-term use leading to increased menstrual flow, which may cause some harm to your body. It is important to note that this medication should not be taken during pregnancy.