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 more limited role because of concerns about its safety.
Estrogen is most commonly given in these forms:
- Pill or tablet
- Vaginal cream
- Vaginal ring insert
- Skin gel
Progestin is available in these forms:
- Pill (can be combined with estrogen)
- Intrauterine device (IUD)
- Vaginal capsule
- Skin gel
What This Medication Is Prescribed For
To Ease Menopausal Symptoms
- Hot flashes
- 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:
- Reduce the symptoms of menopause
- 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
Long-term use of HRT (estrogen plus progestin) may significantly increase women's risks of endometrial cancer,breast cancer, strokes, heart attacks, and blood clots. ERT may also increase the risk of ovarian cancer. HRT has been associated with an increased risk of gastroesophageal reflux disease (GERD).
For many women the risks of HRT—especially when used long-term—may outweigh the benefits, so the decision to use HRT should be carefully considered and discussed with your doctor.
Women with the following conditions are usually advised not to take HRT:
- Unexplained vaginal bleeding
- Liver disease
- Kidney disease
- High levels of triglycerides—a type of fat in the blood
- History of blood clots in the veins
- History of breast or uterine cancer
- History of cardiovascular disease
- History of stroke
- Other conditions—ask your doctor if any of your medical conditions increase the risks of taking HRT
Proper Usage and Missed Dose
You and your doctor will determine the dosing schedule that is best for you. You should have an appointment every 3-6 months while taking HRT to discuss the effects and review your decision. The US Food and Drug Administration (FDA) recommends that women who decide to use HRT for menopausal symptoms use the lowest possible dose for the shortest time needed.
There are two general schedules for taking HRT in pill form:
- Cyclic or sequential—Pills are 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. Then go back to replacing the patch on the same day of the week as before. 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 a 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 so she can take ERT without this risk.
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 that invasive breast cancer was more common among women on long-term HRT.
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.
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 increased risk of heart disease and strokes. However, in another study, the risk of heart attacks and death in recently postmenopausal women was the same as women not taking HRT. Debate continues wether or not HRT increases your risk for heart attacks, but it does increase your risk for strokes. Also, it is well established currently that it does not protect you from heart attacks.
Women on ERT may be at higher risk of ovarian cancer.
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.
Healthy Women—National Women's Health Resource Center, Inc. http://www.healthywomen.org
The American Congress of Obstetricians and Gynecologists http://www.acog.org
Canadian Women's Health Network http://www.cwhn.ca
Women's Health Matters http://www.womenshealthmatters.ca
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9/30/2008 DynaMed's Systematic Literature Surveillance http://www.dynamed.com/topics/dmp~AN~T113927/Hormonal-replacement-therapy-HRT : Jacobson BC, Moy B, Colditz GA, Fuchs CS. Postmenopausal hormone use and symptoms of gastroesophageal reflux. Arch Intern Med. 2008;168(16):1798-1804.
- Reviewer: Michael Woods, MD, FAAP
- Review Date: 01/2017
- Update Date: 01/27/2017