If menstruation is delayed for eight days, the pregnancy test appears a bar, clinically indicate that there is no pregnancy, it is recommended that you can observe for three more days, if there is still no menstruation, you can take progesterone to promote menstruation, it is recommended to take two capsules once a day for three consecutive days, and after stopping the drug, you will have menstruation in three to seven days. If you still do not have menstruation on the eighth day after stopping the medication, it is recommended that you go to the hospital to do the appropriate examination to exclude the possibility of organic lesions. When taking progesterone, you should pay special attention to the following points: First, adhere to the medication every day, do not interrupt the medication, so as not to cause a decrease in the effectiveness of the drug, or the occurrence of irregular vaginal bleeding. Second, if you are allergic to progesterone, you can switch to other drugs to induce menstruation. Third, progesterone is taken orally before going to bed, because progesterone will cause dizziness in about one hour of oral intake.