There are no side effects of progesterone to induce menstruation. Progesterone is a progestin, but it is an exogenous progestin. To induce menstruation with progesterone is only to thicken the endometrium, and after stopping the drug, the endometrium will lose the support of exogenous progestin and there will be withdrawal bleeding to achieve the purpose of inducing menstruation. Do not stop taking progesterone, as any interruption is likely to cause irregular vaginal bleeding. In patients who are allergic to progesterone, oral progesterone should not be used to induce menstruation, but other methods or other medications can be given to induce menstruation. If there is no menstruation on the eighth day after stopping progesterone, in addition to ruling out pregnancy, it is also recommended to rule out the possibility of ovarian failure.