Progesterone Capsules

How Does the Medication Work?

As the name implies, progesterone capsules contain the hormone progesterone. This medication is structurally identical to the progesterone made naturally in the body. In fact, progesterone capsules are the only hormone replacement therapy medication with bio-identical progesterone that has been approved by the U.S. Food and Drug Administration (FDA).
Women who still have a uterus (who have not had a hysterectomy) who take estrogen hormone replacement therapy must also take progesterone or a progestin (a synthetic progesterone-like drug) in order to prevent abnormal thickening of the lining of the uterus caused by the estrogen. This abnormal thickening can lead to cancer of the lining of the uterus. Taking progesterone or a progestin decreases this risk. Of course, this applies only to women who still have a uterus (who have not had a hysterectomy). For women without a uterus, progesterone is usually considered unnecessary.
Progesterone capsules are also approved to cause a period in women who have stopped having periods before menopause for various reasons. Stopping the medication after taking them for a short time (usually ten days) will cause "withdrawal" bleeding (a period) within seven days of the last dose. This mimics the normal drop in progesterone levels that causes regular menstrual periods.

When and How to Use Progesterone Capsules

General considerations for when and how to use progesterone capsules include the following:
  • The medication comes in capsule form. It is taken by mouth once a day at bedtime.
  • For hormone replacement therapy, progesterone capsules are taken 12 days in a row during each 28-day cycle of estrogen medication. You may not have regular periods while taking the medicine.
  • For causing periods in women before menopause, progesterone capsules are taken for 10 days.
  • You can take progesterone capsules with or without food. If the medication bothers your stomach, try taking it with food.
  • For the medication to work properly, it must be taken as prescribed.
Last reviewed by: Kristi Monson, PharmD
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