While benefits and risks of hormone therapy (HT) have been shown in rigorous randomized, controlled trials, clinical use and further study have discovered effects of age, time of HT initiation, and differential effects of various regimens and administration routes on its safety profile. Areas covered: The safety of HT with regard to cardiovascular disease, thrombosis, the endometrium, the breast, and cognition was reviewed. Differential safety effects of estradiol versus conjugated equine estrogens, and progesterone versus synthetic progestins are reported. Expert opinion: Perceived safety of HT has evolved based on data from observational studies, the Women's Health Initiative and its subsequent analyses, more recent randomized, controlled trials, and studies examining the differences between different estrogens and between different progestogens. Unexpected safety concerns with HT became apparent with release of the first results from WHI. Differences between estrogen-alone versus estrogen-progestogen therapies, estradiol versus conjugated equine estrogens, and progesterone versus progestins were found in subsequent WHI analyses and studies examining components of various regimens. The decision to use HT depends on balancing risks and benefits for each individual and determining the most appropriate choice of therapy, dosing, and route of administration, while also considering the safety evidence of different estrogens and progestogens.
Keywords: Conjugated equine estrogens; estradiol; menopause; progesterone; progestins; safety.