Recently, there has been increased interest in custom-mixed (“custom-compounded”) hormone products—recipes containing one or more of various hormones in differing amounts, depending on the individual prescriber’s order. The recipe contains not only the active hormone (or hormones), but also other ingredients that either hold everything together (in the case of a rectal suppository, an under-the-tongue tablet, or an under-the-skin pellet) or provide a vehicle for applying the product onto the skin (such as a cream or gel) or into the body (such as a liquid for a nasal spray). These custom products have the benefit of individualized doses and mixtures of products that are not available commercially. However, risks have also been identified. Although the “active ingredients” (the raw estrogen and/or progestogen components) are government approved, the mixtures are not, because they have not been studied to confirm that they are absorbed appropriately or provide predictable levels in blood and tissue. Thus, there is little or no scientific evidence about the effects of these hormones on the body, either good or bad.