It is not normal for women to have black blood clots during menstruation. If the menstrual flow is normal, black blood clots are caused by Qi stagnation and blood stasis, which can be regulated by taking Chinese herbal medicines, such as Yimu Cao granules and Wuji Baifeng Pills. If the menstrual flow is particularly heavy and the blood clots are particularly large, it may be caused by gynecological diseases, such as endometrial polyps, submucosal fibroids, etc., which may cause the symptoms of black blood clots. You can go to the hospital to improve the examination, find out what causes it, targeted treatment. During the menstrual period, you must be careful to avoid taking drugs that have the effect of activating blood to stop bleeding, so as not to cause disruptions in the menstrual cycle.