It is normal to have a small amount of blood clots during menstruation. Menstruation is bleeding caused by the shedding of the endometrium, which is dark red. Menstrual blood contains thrombin, so menstrual blood is usually non-clotting. When menstrual blood flows out, it is accompanied by the shed endometrium. If a large piece of endometrium is mixed with the menstrual blood, it will form a blood clot, which is normal. If you suffer from endometrial adenomyosis, submucosal fibroids, or functional uterine bleeding, the amount of menstrual bleeding may increase, resulting in larger or more clots, which is abnormal and requires prompt medical attention. In addition, from the Chinese medicine point of view, if there is uterine cold, or if the menstruation is dark or dull in color, accompanied by more blood clots, with symptoms of dysmenorrhea, etc., you need to take warming medication.