Hormone Replacement Therapy (HRT)
Hormone replacement therapy can be either estrogen alone (called estrogen replacement therapy, or ERT), or estrogen and progesterone combined. This combination is referred to as hormone replacement therapy (HRT). Progesterone is usually given in the form of progestins, which are synthetic forms of the naturally occurring hormone progesterone. While once widely used, HRT now has a very limited role because of concerns about its safety.
The information below refers to both HRT and ERT unless noted otherwise.
Medications and Their Commonly Used Names
Estrogen is most commonly given in these forms:
- Pill or tablet
- Vaginal cream
- Vaginal ring insert
- Skin gel
There are many brand names of estrogen replacement medications. For a full listing click here .
Progestin is available in these forms:
- Pill (can be combined with estrogen)
- Intrauterine device (IUD)
- Vaginal capsule
- Skin gel
There are many brand names of progesterone replacement medications. For a full listing click here .
What This Medication Is Prescribed For
To Ease Menopausal Symptoms
- Hot flashes
- Sleep disturbance
- Vaginal dryness
To Reduce the Risk of Osteoporosis and Related Fractures
Estrogen is important for bone health. When the natural supply of estrogen drops off with menopause, HRT can help protect bones by replacing estrogen.
How This Medication Works
The hormones provided with HRT are meant to replace the natural hormones that a woman's body no longer produces after menopause. Estrogen is involved in many functions in the body, and therefore, HRT is believed to provide the following benefits:
- Helps to slow or prevent the bone loss that occurs with aging and increases after menopause, in order to help delay osteoporosis
- Helps to reduce the risk of colorectal cancer
Precautions While Using This Medication
The long-term use of HRT has been based on assumptions that it would prevent heart disease and osteoporosis. However, a major study suggests that the long-term use of HRT (estrogen plus progestin) significantly increases women's risks of breast cancer , strokes , and heart attacks , and blood clots. Another major study suggests that estrogen replacement therapy (ERT) increases the risk of ovarian cancer . HRT has also been associated with an increased risk of gastroesophageal reflux disease (GERD).
Since for many women the risks of HRT—especially when used long-term—may outweigh the benefits, the decision to use HRT should be carefully considered and discussed with your healthcare provider.
Women with the following conditions are usually advised not to take HRT:
- Liver disease
- High levels of triglycerides (a type of fat in the blood)
- History of blood clots in the veins
- History of breast or ovarian cancer
- History of cardiovascular disease
Proper Usage and Missed Dose
You and your doctor will determine the dosing schedule that is best for you. You should see your doctor at least once a year while taking HRT to discuss the effects and to review your decision.
There are two general schedules for taking HRT in pill form:
- Cyclic or sequential—Estrogen is taken every day for a set number of days. A higher dose (than that used in continuous doses) of progestin is given for 10-14 days. One or both hormones are stopped for a specified period of time. This pattern is repeated every month, and it causes regular monthly bleeding like a light menstrual period.
- Continuous—Low-dose estrogen and progestin are taken together every day of the month without any break. Vaginal bleeding often occurs, sometimes for up to a year when this schedule is first started, and can vary from light spotting to irregular menstrual-type bleeding.
Take estrogen at the same time every day to minimize side effects. If you are using an estrogen skin patch, be sure to read the application directions carefully before using.
- Pill form—If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
- Skin patch—If you forget to apply a new patch when you are supposed to, apply it as soon as possible. However, if it is almost time for the next patch, skip the missed one and go back to your regular schedule. Always remove the old patch before applying a new one. Do not apply more than one patch at a time.
Possible Side Effects
The following side effects may disappear over time as your body adjusts to taking HRT. Also, your doctor may be able to change the amount of hormone you receive, the way it is taken, or the timing of the dose, in order to help minimize these effects:
- Breast tenderness
- Return of monthly periods
- Swelling of feet and lower legs
- Rapid weight gain
HRT can also cause some very serious side effects. You should discuss your specific health status and risks with your doctor when deciding whether or not to use HRT. These serious side effects include the following:
For woman who has not had her uterus removed (via a hysterectomy ), taking estrogen alone (ERT) can lead to cancer of the endometrium (the lining of the uterus). However, this risk can be avoided by taking both estrogen and progestin in the form of HRT. A woman who has had her uterus removed cannot develop endometrial cancer and, therefore, can take ERT.
Some studies have suggested that women who take HRT and ERT are at greater risk for developing breast cancer. A major study on HRT, the Women's Health Initiative, found 26% more invasive breast cancers among the women who were on long-term HRT than those who were not taking HRT. Of 10,000 postmenopausal woman who took HRT, eight more developed breast cancer than a similar group of 10,000 women who were not taking these hormones.
Both HRT and ERT slightly increase the risk of developing blood clots in veins. In the Women's Health Initiative study, women who were long-term users of HRT had twice the number of blood clots as the women who were not taking HRT. Of 10,000 postmenopausal women who took HRT, 18 more developed blood clots than a similar group of 10,000 women who were not taking these hormones.
Although HRT was previously believed to reduce the risk of cardiovascular disease, it appears that long-term use of HRT may actually increase this risk. In the Women's Health Initiative study on HRT, women on long-term HRT had 41% more strokes and 29% more heart attacks than did the women who did not take HRT. Of 10,000 postmenopausal women who took HRT, seven more had heart attacks and eight more had strokes than a similar group of 10,000 women who were not taking these hormones.
Results from the Women's Health Initiative study on ERT suggest that ERT increases the risk of ovarian cancer. The study showed that, compared with women who never took hormone replacement therapy, those who took ERT were 60% more likely to develop ovarian cancer. The risk seemed to increase the longer the women took ERT.
Other Uses for This Medication
To treat the following:
- Osteoporosis caused by lack of estrogen before menopause
- Turner's syndrome (a genetic disease)
With every medication, there are important precautions to consider. These include allergies, interactions with other drugs and medical conditions, and safety in certain age groups.
American Congress of Obstetricians and Gynecologists
National Women's Health Resource Center
The Canadian Women's Health Network
Women's Health Matters
American College of Obstetricians and Gynecologists website. Available at: http://www.acog.org .
Hormone replacement therapy. National Institute on Aging website. Available at: http://www.nia.nih.gov/ .
Hormone replacement therapy and breast cancer risk. American Medical Women's Association website. Available at: http://www.amwa-doc.org .
¹9/30/2008 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Jacobson BC, Moy B, Colditz GA, Fuchs CS. Postmenopausal hormone use and symptoms of gastroesophageal reflux. Arch Intern Med. 2008;168:1798-1804.
Last reviewed January 2009 by Jeff Andrews, MD, FRCSC, FACOG
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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