Does vaginal estrogen cream carry the same risks as systemic hormone therapy?

DEAR DOCTOR K:

I use a vaginal estrogen cream for vaginal dryness. Does it have the same risks as hormones taken orally or by skin patch?

DEAR READER:

Hormone therapy (HT) is estrogen taken alone or with other female hormones to treat the symptoms of menopause. “Systemic” HT involves hormones that enter the blood and travel throughout the body. It is the most effective treatment for postmenopausal hot flashes and vaginal symptoms, including vaginal dryness.

Systemic HT is medicine taken by mouth or through the skin by a skin patch or gel. From those locations, it enters into the blood. But systemic HT carries with it a small risk of several serious conditions: heart attacks, stroke, blood clots and some cancers.

To find out if there are similar risks associated with vaginal estrogen, I checked in with my colleague Dr. Celeste Robb-Nicholson, editor-in-chief of the Harvard Women’s Health Watch.

She pointed out that vaginal estrogen acts mostly in the vagina. It relieves vaginal symptoms, including vaginal dryness, burning, and pain with sexual intercourse. It does not relieve hot flashes. (One exception is a vaginal ring, called Femring. It delivers so much estrogen in the vagina that some of it is absorbed into the blood and therefore has effects throughout the body.)

Low-dose vaginal estrogen is available in several forms: creams, tablets and other kinds of vaginal rings. Vaginal creams are applied to the vulva or in the vagina. Vaginal tablets (Vagifem) are inserted in the vagina. And a flexible vaginal ring, called Estring, is worn continuously and replaced every few months.

The Vagifem tablet contains the lowest amount of estrogen. Estring delivers just a bit more. Vaginal estrogen creams are more concentrated; the amount of estrogen that a woman absorbs varies.

Vaginal application releases little estrogen into the bloodstream. As a result, it has less risk of side effects than systemic estrogen. So far, no well-designed clinical trials have evaluated systemic risks, such as breast cancer or blood clots, of low-dose vaginal estrogen. But it’s likely that if there are such risks, they are much smaller than the risks related to systemic estrogen.

One complication of menopause that women don’t often think of is recurrent urinary tract infections (UTIs). Vaginal dryness not only causes vaginal symptoms such as discomfort during sex, but also encourages the growth of certain bacteria around the urethra — the tube that carries urine from the bladder to the vagina. If those bacteria get into the urethra, and then into the bladder, a UTI can start.

Apart from the high-dose Femring, vaginal estrogen is probably safe even over the long term. And if your main menopausal symptoms are vaginal symptoms, vaginal estrogen is just as effective as systemic HT and less risky. But talk to your doctor about the risks and benefits before you start — particularly if you have a history of breast cancer.