You can take Colla Corii Asini before menstruation, but there are certain indications for taking Colla Corii Asini. Colla Corii Asini is used clinically in Chinese medicine for patients with deficiency of qi and blood, or patients with qi stagnation and blood stasis, which can be regulated by Colla Corii Asini. Therefore, before women take Colla Corii Asini, they must look at the menstrual condition. If the menstrual blood is heavy and there are blood clots during the period, it is not recommended to take Colla Corii Asini. If there are patients with deficiency of qi and blood, they can be treated with Colla Corii Asini to replenish and nourish the blood. So whether women are suitable to use Colla Corii Asini needs to be based on the situation. Normally, women with 20-60 ml of menstrual flow is normal, less than 20 ml is low menstrual flow and more than 80 ml is excessive menstrual flow. Patients with low clinical menstrual flow and delayed menstruation can consider using it and can take Colla Corii Asini before menstruation to regulate it.