More than half of women studied who stopped taking hormone replacement therapy saw their menopausal symptoms return, but lifestyle changes may help.

In 2002, the Women's Health Initiative trial was stopped early because researchers discovered combined estrogen and progestin therapy increased women's risk of breast cancer, heart disease and stroke, compared to those taking a placebo.

Official guidelines now recommend women take hormone therapy for menopausal symptoms for the shortest time possible and at the lowest dose.

The abrupt conclusion to the trial gave doctors a chance to look at the effects of ending therapy in more than 8,000 women with an average age of 69.

Among women who reported problems such as hot flashes or night sweats at the beginning of the study, 56 per cent on HRT reported the symptoms returned, compared to 21 per cent for those taking a placebo.

Four out of five women who reported trying non-pharmaceutical strategies said these provided some relief. Drinking more fluids and starting or increasing exercise were reported by more than 20 per cent of women in each treatment group described in the July 13 issue of the Journal of the American Medical Association.

Judith Ockene of the University of Massachusetts Medical School and her co-authors recommend further tests on the effectiveness of such lifestyle strategies that carry minimal risk.

The high frequency of symptoms reported may also be a result of stopping hormone or placebo therapy so abruptly, noted Dr. Diana Petitti of Kaiser Permanente Southern California.

"When it is time to consider discontinuing hormone therapy, gradual tapering off the dose would be a logical clinical strategy arising from these new observations," Petitti wrote in a journal commentary.

The data on "placebo withdrawal effect" and relief from lifestyle changes also raise questions about the physiological basis of some symptoms linked to menopause, Petitti said.

Little is known about distinguishing what could be symptoms of ovarian aging, such as night sweats or vaginal dryness, compared to symptoms of aging in general for both sexes, including aches and tiredness.