Progesterone (proe JES ter one) is a female hormone. This medicine is used to prevent the overgrowth of the lining of the uterus in women who are taking estrogens for the symptoms of menopause. It is also used to treat secondary amenorrhea. This is when a woman stops getting menstrual periods due to low levels of progesterone. This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.