Women can take hormones after menopause to alleviate hot flashes and vaginal dryness and perhaps to stave off osteoporosis if they are at high risk for thinning bones, but should always use the lowest doses for the shortest possible time, the federal government advised yesterday.

In its first detailed guidance about post-menopausal hormone use since the discovery of new risks from the drugs caused widespread confusion and anxiety last summer, the Food and Drug Administration also said women should not take estrogen or combinations of estrogen and progesterone to reduce their risk for heart disease.

In fact, the agency ordered yesterday that all products containing estrogen must now include a prominent warning on their labels that extended use could increase the risk of heart attacks, stroke, breast cancer and potentially life-threatening blood clots.

Women who suffer from vaginal dryness and similar problems should try using topical creams or gels instead of hormones, the agency said. And women at risk for osteoporosis should also explore alternatives, the FDA said.

"Our goal is to try to clear up the confusion," FDA Commissioner Mark McClellan said in a telephone briefing with reporters.

"The main message that women need to take away is that the decision about hormone use is a decision that needs to be individualized. There are clear benefits and clear risks associated with estrogen. Our goal in this guidance is to help women and their health care providers make informed decisions about the risk and benefits."

The FDA's actions apply to any product containing either estrogen alone or estrogen and progesterone combined, even though only Wyeth Pharmaceutical's best-selling combination of estrogen and progesterone, called Prempro, was specifically shown to carry risks.

"In the absence of data suggesting otherwise, women have to assume" that all hormones are equally risky, McClellan said.

Millions of women have been taking hormones for years to relieve hot flashes, night sweats and vaginal dryness, to keep their bones from thinning and to reduce their risk for heart attacks.

In July, the National Institutes of Health prematurely halted part of a large, ongoing federal study after it became clear that the risks from hormone replacement therapy outweighed the benefits for most women.

Not only did the hormones fail to reduce the risk for heart disease, as expected, but the drugs increased the chances that women would suffer heart attacks, strokes, breast cancer and blood clots.

The announcement came as a shock to women and doctors, and caused widespread uncertainty about exactly what they should do. Hormone use plummeted.

Yesterday's advice from the FDA was welcomed by doctors, women and women's health advocates.

"I think this will help women and their health care providers begin to put this into perspective," said Wulf H. Utian, executive director of the North American Menopause Society.

"In the first few months, the baby got thrown out with the bath water. There was major confusion," he said.

"Women in the hundreds of thousands came off treatment, and many of them became extremely miserable. I think the medical world and consumers have begun to realize there was a difference between using these products for symptomatic relief and in a preventive role."

But Utian disagreed with the FDA's decision to apply the findings to all hormone products. "I don't think that's fully justified," Utian said.

"I think it adds to the confusion when they lump estrogen and estrogen and progesterone together."

Amy Allina of the National Women's Health Network said the action was "the first thing from FDA that's really oriented towards helping health care providers and women figure out how to change their practice. I think this will help women and their health care providers have better conversations."

Wyeth Pharmaceuticals, based in Saint Davids, Pa., said it was sending revised prescription information to more than half a million doctors and other health care providers.

"We believe it is in the best interests of patients and physicians that all manufacturers of [hormone] products act quickly to modify their prescribing information," said Wyeth Vice President Victoria Kusiak in a statement.

Other companies had attempted to capitalize on this summer's announcement, because only Prempro had been proven risky. A spokeswoman for Pfizer Inc., which makes a competing product known as FemHRT, would say only that the company was reviewing the FDA's new requirements and would work with the agency on new labeling.

The FDA also said it would soon be providing drug companies with specific information they can use to design studies to evaluate the safety of their products.