Natural progesterone (non-micronized or bio-identical progesterone) may be bought over the counter or compounded by a physician, as well as prescribed, but the FDA only maintains strict quality control over the pharmaceutical industry. If you are interested in a natural (or bio-identical) progesterone, look for those available pharmaceutically, either in pill form (Prometrium) or in gel form (Crinone).With natural over-the-counter progesterone or compounded formulation, you may not know exactly what you're getting; the dosage and absorption rate on these products usually are not well studied or documented. Also, over-the-counter products and compounded formulations may not have package inserts listing the risks, benefits and contraindications.Over-the-counter forms of natural progesterone probably are not as effective as progestins or micronized progesterone.In particular, progesterone creams should not be used as a substitute for progestins in combination with estrogen replacement for treating menopausal symptoms. There is no evidence that they protect against endometrial cancer like progestins or micronized progesterone.There are other roles for natural progesterone, however. The U.S. Food and Drug Administration has approved Crinone, a vaginal gel formulation of natural progesterone for treatment of amenorrhea and for infertility procedures, and Mirena, an intrauterine device that delivers progesterone directly to the uterus is an effective form of birth control and is sometimes used to treat abnormal uterine bleeding.