Dark red menstrual blood is usually normal because menstrual blood is different from normal blood in that it contains white blood cells, red blood cells, vaginal epithelial cells, as well as shed endometrial debris and cervical mucus, so menstrual blood is darker than normal blood and is dark red in color. As a period progresses, menstrual blood starts out as a lighter dark red color, then deepens in color and finally becomes light red to clean. However, it should be noted that if the color of menstruation is too dark or even black, or if it is accompanied by abnormalities such as excessive blood clots, odor, excessive menstrual volume, irregular bleeding, etc., it may be caused by endometrial cancer, cervical polyps, gynecological tumors, pelvic inflammatory disease and other related diseases, and the menstrual blood stays in the uterine cavity for too long, so it should be taken seriously and needs to be checked in a regular hospital. Women should pay attention to hygiene during menstruation, change sanitary napkins regularly, pay attention to personal hygiene, do not sit in the bath. Avoid sexual intercourse, eliminate all behaviors that may lead to gynecological infections, pay attention to keeping warm, and if the color of menstrual blood is abnormal or accompanied by other abnormalities, you need to seek medical attention as soon as possible.