Compounded bioidentical hormones are plant-derived hormones, biologically similar or identical to those produced by the body, that can be custom prepared by a pharmacist based on physician specifications. These agents are controversial, however, because of concerns related to quality, purity, potency, and effectiveness. A committee of the American College of Obstetricians and Gynecologists (ACOG) has released a report on compounded bioidentical hormones, which was published in the November 2005 issue of Obstetrics & Gynecology.

No rigorous clinical trials have tested the safety or effectiveness of bioidentical hormone regimens. However, 10 out of 29 other compounded products failed one or more quality tests when analyzed by the U.S. Food and Drug Administration (FDA) compared with the 2 percent failure rate of FDA-approved agents. Because bioidentical hormones are not FDA approved, manufacturers are not required to provide official labeling that would list warnings or contraindications.

ACOG considers bioidentical hormones to have the same safety issues as the drugs that require approval by the FDA, along with possible additional risks associated with compounding. ACOG also concludes that there is no scientific evidence to support claims that these agents are safer or more effective than individualized estrogen or progesteronetherapy.