Thick menstrual blood like big snot may be a normal physiological phenomenon, or it may be caused by endometritis, vaginitis and other diseases. 1. Normal physiological phenomenon: menstrual blood is caused by cyclical shedding of the endometrium and bleeding. If the endometrial tissue is peeled off more, and the blood mix is less, it can cause menstrual blood to be sticky like big snot, which is a normal physiological phenomenon. 2. Endometritis: refers to the inflammatory reaction of the endometrium due to various reasons. The main manifestations are pain and discomfort in the pelvic area, abnormal leukorrhea, increased menstruation, dysmenorrhea and other symptoms, which can also cause menstrual blood to be thick like big snot. 3. Vaginitis: vaginal inflammation caused by various types of pathogens, common bacterial vaginitis, trichomonas vaginitis, etc., mainly manifested as vulvar or vaginal itching, burning pain, accompanied by abnormal leukorrhea, menstruation can be manifested as an increase or decrease in the amount of menstruation or viscous, which may be accompanied by a peculiar smell, can also cause menstrual blood thick like a big snot. There are many other causes of menstrual blood thick like big snot, which should be taken seriously, timely consultation, identification of the cause of the disease, and follow the doctor’s advice for further treatment or therapy.