Think this sums it up well:
The International Menopause Society, American Congress of Obstetricians and Gynecologists, Society of Obstetricians and Gynaecologists of Canada, the Endocrine Society, the North American Menopause Society (NAMS), United States Food and Drug Administration, American Association of Clinical Endocrinologists, American Medical Association, American Cancer Society and the Mayo Clinic have released statements that the there is a lack of evidence that the benefits and risks of bioidentical hormones are different from well-studied nonbioidentical counterparts, that until such evidence is produced the risks should be treated as if they were similar, and that compounded hormone products may have additional risks related to compounding. A major safety concern of bioidentical hormone replacement therapy is that there is no requirement to include package inserts despite the potential for serious adverse effects, including life threatening adverse effects, being associated with HRT. This can lead to consumers being deceived and even harmed as they are mislead into believing that BHRT is safe and has no side effects.