Prempro is a drug that contains a form of estrogen, called Premarin, and a form of progesterone, called Provera. It is most often prescribed to treat hot flashes and other symptoms in perimenopausal women.

The estrogen treats the symptoms. The progesterone counteracts the effects of estrogen on the uterus. Estrogen can increase the risk of uterine cancer if taken alone. Adding progesterone prevents this. A woman who has had a hysterectomy does not need to take progesterone when using estrogen.

Prempro is the most extensively studied brand name drug used for hormone therapy, but it is not the only one available. A generic form of estrogen called estradiol can be used instead of Premarin. It costs about $13 per month. The generic form of Provera is called medroxyprogesterone acetate. It also costs about $13 per month. The combined cost of these two drugs is much less expensive than using brand name Prempro.

A woman who uses hormone therapy should be monitored by her doctor. The Women's Health Initiative study showed that the prolonged use of hormone therapy after menopause was associated with an increase in the risk of breast cancer. The current guideline is to use the lowest effective dose for the shortest period of time needed to control menopausal symptoms.