Estrogen-only pills increase older women's risk for blood clots

Estrogen pills raise older women's risk of blood clots, but not as much as supplements that also contain progestin, according to new data from a landmark study on more than 10,000 women.

The U.S. government study is the most rigorous to date to link estrogen-only pills with blood clots in healthy women past menopause.

The study appears in Monday's Archives of Internal Medicine.

While the results were not entirely unexpected, they add to a long list of complications found by the Women's Health Initiative, a large government-sponsored research project that has contradicted long-held assumptions that hormones taken at menopause promote health and postpone age-related ills.

In 2002, the WHI linked estrogen-progestin pills to heart attacks and breast cancer and found that they also doubled the risk of blood clots. As a result, millions of U.S. women stopped taking supplements.

"Most of us didn't anticipate we would be going through this list of negatives when we started 10 years ago," said Dr. J. David Curb, a geriatrics professor at the University of Hawaii and lead author of the estrogen-only study.

"Unfortunately the list just keeps growing," he said. "Almost everything we look at is a negative effect, except for relief of symptoms in women who have severe symptoms."

Women who had had previous clots faced the highest risk of developing new clots during the estrogen-only study. As a result, the researchers said estrogen use should be discouraged in such women unless they are taking blood thinners.

Other menopausal women who choose to take hormones should use them only for severe hot flashes and related symptoms, on a short-term basis, they said, reports AP.

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