Facts about estrogen

Susan Ott, M.D.

Who should take estrogens?

There is still a lot of controversy about estrogens, but everybody agrees they are good for the bones. Estrogens improve bone density as well or better than bisphosphonates, and estrogens decrease the risk of osteoporotic fractures. Estrogens can be given to women who are within 5 years of menopause, and who have a risk of developing osteoporosis. They also help with menopausal symptoms such as hot flashes, vaginal dryness, and sleep disturbances. Estrogens should not be started in women who are more than 10 years past menopause because they might worsen heart disease, but estrogen can protect against heart disease when given right after menopause. Estrogens should be avoided in women who have had blood clots or breast cancer. In women who have a uterus, estrogen can cause cancer of the lining of the uterus, so another female hormone called progesterone should be given to protect the uterus. However, progestins markedly increase the risk of breast cancer, so the safest way is to use an interuterine device which contains progesterone. An alternative is to give small doses of progesterone every 3 or 4 months, which will usually induce a period. This approach needs further study to be sure it is safe, but so far it seems to work well.


Estrogens come in patches applied to the skin or in pills. Both work for the bones. The patches might cause less blood clotting, and the pills result in better cholesterol profiles. The choice must be made on an individual basis.

Side effects

  • Breast tenderness may occur. This usually gets better in several weeks.
  • Vaginal bleeding is common. This depends also on the kind of progesterone that is used. Adjustments should be made if bleeding is a problem, but it may take several months to reach a regular pattern (cyclical progesterone).
  • Mood changes are noted by some women.
  • Skin or hair changes may be seen sometimes, usually this is not a serious problem.
  • Nausea may be seen, especially if the dose is too high.
  • Blood clots (thrombophlebitis) occur within a year in about 1 of 280 women, probably in those who have a genetic tendency. These generally are in the calf, which becomes tender or swollen on one side. If this happens you should see a doctor right away to get checked for a blood clot.
  • Gallstones are twice as common in women taking estrogen. They cause nausea, abdominal pain or bloating, especially after eating a meal with fatty foods.
  • Breast cancer risk may increase slightly after long-term estrogen, but in the first 5 years there are more cases in women taking a placebo than in women taking estrogen without progestin.


  • If you are taking thyroid, the dose should be adjusted.
  • If you have migraine headaches, uterine fibroids, high triglycerides in your blood, lupus, chronic liver disease or endometriosis, you should ask your physician if it is OK to take estrogen.
  • Women who take estrogen gain less weight than women who don't.