HRT-Benefits, Risks and Side Effects
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Benefits, Risks and Side Effects of ERT, HRT, and NHRT

What are the benefits of ERT, HRT, and NHRT?
Risks and side effects of HRT
Who should not use HRT?

What are the benefits of ERT, HRT, and NHRT?

ERT, HRT, and NHRT can all help relieve menopausal symptoms such as hot flashes, night sweats, sleep problems, and vaginal dryness. Estrogen can also prevent bone loss that leads to thin, weak bones (osteoporosis). HRT may help prevent other diseases such as colon cancer and macular degeneration (age-related vision loss), and may help delay the onset of Alzheimer's disease.

There is some evidence that transdermal estrogen may be helpful in treating depression and in improving symptoms in female Alzheimer’s patients. Estrogen, especially oral estrogen, can help improve cholesterol levels, but in recent studies, that has not translated into a reduced risk of heart disease. (See below.)

The benefits of estrogen replacement therapy are not yet fully known and understood, and much remains to be learned about the differing effects of ERT and HRT in their various formulations. For example, oral and transdermal estrogens have somewhat different effects because of the way the estrogen enters the body. More research is needed to clarify these effects.

Risks and side effects of HRT

There are a number of risks and side effects associated with HRT. It is difficult to determine the extent to which NHRT is associated with most risks and side effects because of the lack of long-term clinical trials using NHRT or comparing bio-identical hormone replacement with other forms of HRT in the United States.

HRT risks and possible side effects include:

  • Increased risk of endometrial cancer in women with a uterus if estrogen is taken without progesterone or a progestin
  • Slightly increased risk of breast cancer after 4 or more years of HRT, as shown in the WHI study that used continuous combined oral estrogen and progestin (Prempro). Estrogen alone or other HRT regimens may not raise the risk of breast cancer significantly.
  • Increased breast density, making mammograms more difficult to interpret and possibly increasing breast cancer risk. This appears to be an effect primarily associated with taking oral progestin continuously with estrogen (e.g., Prempro).
  • Slightly increased risk of ovarian cancer
  • Slightly increased risk of blood clots, associated primarily with oral estrogens such as Premarin*
  • Increased risk of gallbladder disease, associated primarily with oral estrogens such as Premarin*
  • Slightly increased risk of heart attack or stroke, both in women with cardiovascular disease and in healthy women. This effect may be associated primarily with HRT using continuous combined oral estrogen and progestin (Prempro) or the daily use of an oral progestin such as Provera with estrogen.
  • Breast pain (often a temporary problem)
  • Nausea, associated primarily with oral estrogens*
  • Bloating and fluid retention, primarily associated with progestins, e.g., medroxyprogesterone acetate
  • Negative effects on mood, primarily associated with progestins, e.g., medroxyprogesterone acetate

*Note: These side effects seem to be associated with oral estrogen and not with transdermal estrogen.

Monthly vaginal bleeding often occurs when women take estrogen and progestin in a cyclical style (usually estrogen every day, but progestin only part of the month) rather than all the time. Spotting or bleeding may also occur when HRT is taken in the continuous combined style (both estrogen and progesterone or progestin every day). Problems with bleeding and spotting may improve over time or with a change in dose, regimen, or type of progestin/progesterone used. Women who do not want any bleeding at all may find these effects unacceptable.

Some women find that trying a different type of HRT, such as switching to bio-identical hormones, using a transdermal product instead of pills, or trying a different regimen, may reduce or eliminate side effects and work better for them.

Who should not use HRT?

HRT is usually not recommended for women who have:

  • Vaginal bleeding for no known reason
  • A history of breast cancer
  • A history of cancer of the uterus
  • Liver disease
  • Blood clots in the veins or legs, or in the lungs. This includes women who have had blood clots during pregnancy or when taking birth control pills.
  • Cardiovascular disease (diseases of the heart and blood vessels)

For a long time, it was thought that ERT and HRT reduced the risk of heart disease, based on large observational studies that found lower rates of heart disease in ERT and HRT users. However, research has found that women who have had a recent heart attack or a stroke are more likely to have a second heart attack or stroke if they start taking HRT. For this reason, starting HRT is not recommended for women with cardiovascular disease. In addition, as the WHI study showed, even healthy women who begin HRT (at least with Prempro) may have a slightly increased risk of heart attack or stroke in the first year or two of therapy.

To read the latest information about the WHI studies on HRT, its risks, benefits and side effects, visit the National Heart, Lung and Blood Institute's web site.

Because of these research findings, the American Heart Association has recommended that HRT not be given to women solely in order to prevent heart disease, and that women with heart disease or who have had a stroke should not start taking hormones. Recent research has suggested that the effects of estrogen on the cardiovascular system vary according to the mode of delivery of estrogen (oral versus transdermal). In addition, the effects of estrogen seem to be affected by the addition of a progestin, androgen, or a statin (cholesterol-lowering class of drugs). Much remains to be learned about these interactions and effects.


Please read on...

  What Is Hormone Replacement Therapy (HRT) and Why Would I Need It?
   What Hormones Are Used in HRT? and How Is HRT Taken?
  About Estrogen
  About Progesterone
  Benefits, Risks and Side Effects of ERT, HRT, and NHRT
HRT and Breast Cancer
  Androgens, SERMs and Other Drugs for Menopause
  What Are Some Alternatives to Standard HRT?

Resources and References


Page uploaded September 2002






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Adrenal Fatigue
Cortisol and Weight
DHEA or Testosterone for Women
Estrogen and Memory Loss
HRT for Breast Cancer Survivors and Women at High Risk for Cancer
Human Identical Hormones
Premarin, Facts and Opinions
Progesterone FAQ
Synthetic Progestins and Natural Progesterone, Differences
Natural Progesterone, What Role in Women's Healthcare
Tamoxifen for Prevention of Breast Cancer
Testosterone and Its Benefits to Women
Testosterone's Impact on Postmenopausal Women...
Thyroid Hormone, Symptoms, and...
Typical HRT Products
Where to get Natural Hormones
Herbal Allies, An Introduction
Alternative Remedies for Menopausal Symptoms






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Updated 09/29/2010