Didroxyprogesterone tablets are a kind of progestin medication used to regulate menstruation for 3 months, 3 months being a course of treatment. It is mainly used for patients with insufficient progesterone level in the body, such as those with luteinizing insufficiency, who tend to have shortened menstrual cycles and may have periods once every 20 days. In some cases, although the menstrual cycle is normal, the menstrual period may take longer, taking about 10 days to clear. This is mostly due to the luteal body not shrinking in time, and progesterone is also needed for regulation.