A study by the Women's Health Initiative showed that hormone replacement therapy — both solely estrogen and estrogen-and-progestin — had significant risks. It increased the risk of breast cancer, stroke and blood clots and did not, as predicted, lower the risk of heart disease. Given the danger, hormone replacement therapy should be prescribed on a case-by-case basis. It is currently approved for postmenopausal symptoms, though women who do start hormone replacement therapy are encouraged to try the smallest dose for the shortest amount of time, according to the Food and Drug Administration. Only women with a severe risk of osteoporosis who cannot take non-estrogen therapies should be considered for using hormone replacement therapy preventatively.