Ask the doctor: Does vaginal estrogen have the same risks as oral or patch estrogen?

Q. Do vaginal estrogens that are used for vaginal dryness have the same risks as estrogens taken orally or by skin patch?

A. Hormone therapy (HT) — estrogen given alone or with progesterone or a progestin (to protect the uterine lining, or endometrium) — is the most effective treatment for postmenopausal hot flashes and vaginal symptoms. However, systemic HT, which acts throughout the body and is measurable in the blood, is associated with increased risk for heart disease, stroke, blood clots, breast cancer, and gallbladder disease, although we don't know the exact relationship between these risks and differences in dosage, timing, modes of administration, and factors such as age. The main types of systemic HT are oral and transdermal, such as a skin patch or gel. A vaginal ring called Femring also delivers estrogen at a dose high enough to have systemic effects.