If you take Yunnan Baiyao on the first day of menstruation, it will reduce the amount of menstruation. Yunnan Baiyao mainly has the efficacy of stopping bleeding, and menstruation is a normal physiological phenomenon, so it is not recommended to take Yunnan Baiyao on the first day of menstruation to interfere with normal menstruation if there are no special circumstances. Yunnan Baiyao will change the menstruation and make the menstruation clean as soon as possible after taking it, which may affect the next menstruation accordingly, so it is recommended to follow the natural law. If there are special circumstances, you can take Yunnan Baiyao and keep taking it until your period clears, otherwise if you stop taking the medicine after one day in between, you may have your period again. During menstruation, you should pay attention to keep warm, and you can’t take antiemetic drugs, blood-activating drugs or hormone drugs without medical advice.