Harvard Women's Health Watch

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.

Low-dose vaginal estrogen (creams, tablets, and a vaginal ring called Estring) acts predominantly locally, mostly in the vagina. It relieves vaginal dryness, burning, and pain with sexual intercourse, but not hot flashes. Vaginal estrogen doesn't raise blood levels of estrogen enough to stimulate the overgrowth of endometrial cells, so it's thought that progesterone isn't needed. So far, no well-designed clinical trials have evaluated systemic risks, such as breast cancer or blood clots, in women using low-dose vaginal estrogen. But it's unlikely that the risks are similar to those of systemic estrogen.

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