Progesterone capsules contain a form of progesterone that is chemically identical to the hormone naturally produced in the body. They are primarily prescribed for postmenopausal women who are taking estrogen to manage symptoms of menopause. In this context, progesterone helps prevent the overgrowth of the uterine lining (endometrial hyperplasia), a condition that can increase the risk of uterine cancer. Additionally, this medication is used to restore normal menstrual periods in women whose cycles have stopped prematurely due to a lack of natural progesterone.

Progesterone's main role is to prepare the lining of the uterus (the endometrium) for pregnancy after ovulation. When used as part of hormone replacement therapy, progesterone counteracts estrogen's continuous stimulation of the endometrium. This leads to a controlled shedding of the lining, similar to a menstrual cycle, which prevents it from becoming too thick. For treating menstrual irregularities, providing progesterone helps mimic the natural hormonal cycle, signaling the uterus to shed its lining and thereby re-establishing a more regular pattern of periods.

Progesterone capsules are typically taken orally, once daily at bedtime, as they can cause significant drowsiness and dizziness. The dosing schedule may be continuous or cyclical (for a certain number of days each month), as determined by your healthcare provider. It is crucial to inform your doctor of your complete medical history, particularly any history of breast cancer, liver disease, or blood clots. Some formulations contain peanut oil and should not be used by individuals with a peanut allergy. Regular follow-ups with your doctor, which may include pelvic exams and mammograms, are necessary to monitor your health while on this therapy.