Progesterone injection will not be painful at that time, because the progesterone injection is an oil, so the absorption is slow, and local pain may occur after the injection. It is recommended to use hot compresses locally to promote the absorption of progesterone. If in the clinical intramuscular injection of progesterone to promote menstruation, three consecutive days of injection, 3-7 days after stopping the drug will come to menstruation. It is recommended that if the drug can be taken orally, it is best not to inject it intramuscularly, so as not to cause local drug non-absorption and the formation of hard knots, and cause pain. If it is used to stabilize the fetus, in the clinic the duration of the progesterone injection should be until the progesterone returns to normal after the laboratory examination, and then consider stopping the drug. In addition, the principle of using the drug is that if it can be taken orally, not intramuscular injection, and if it can be injected intramuscularly, not intravenous drug.