General gastrointestinal function of the drug caused by the delay in menstruation chances are very low, the current menstruation has been delayed for 13 days of time, the first thing to rule out the chances of there is no pregnancy occurs, because there is a part of the women when there is an early pregnancy reaction, nausea, vomiting and even intestinal function confusion, think it is a stomach disease, so will take their own stomach pills, at this time must first rule out the chances of there is no pregnancy occurs, if you determine that there is no pregnancy. If you are sure that you are not pregnant, you can go to the hospital and register with the gynecology department for an ultrasound examination to determine the thickness of the uterine lining. Also to determine whether the uterus double annexes are abnormal, according to the situation of oral menstruation drugs, to avoid prolonged delay, and at the same time to observe the situation of the next month, if a long period of irregular menstrual cycles, to check the endocrine hormones, if necessary, can be oral short-acting contraceptives, cycle regulation, to avoid prolonged cause menstrual cycle confusion.