Hormone Replacement Therapy (HRT)

Search Knowledgebase

Topic Contents

Hormone Replacement Therapy (HRT)


Hormone replacement therapy (HRT) refers to the use of estrogen plus progestin for the treatment of perimenopausal symptoms.

Estrogen and progestin combinations (pills or tablets)

Generic NameBrand Name
conjugated estrogens/medroxyprogesteronePremplus

Transdermal combination preparations (a patch placed on the skin that continuously releases estrogen and progestin)

Generic NameBrand Name
estradiol/norethindrone acetateEstalis

Oral progestin (pills or tablets; used along with an estrogen-only preparation)

Generic NameBrand Name
micronized progesteronePrometrium
norethindroneMicronor, Nor-QD

Progestin intrauterine device (IUD; used along with an estrogen-only preparation)

Generic NameBrand Name

Estrogen-progestin hormone therapy, or HRT, is recommended for all women with a uterus who choose to take estrogen. Using estrogen without progestin greatly increases your risk of endometrial cancer. Taking progestin with estrogen eliminates this increased risk.5

How It Works

HRT increases the estrogen and progestin levels in your body. There are several standard hormone replacement therapy schedules, including continuous and cyclic along with higher-dose and low-dose.

Combining progestin with estrogen:

  • Protects against endometrial cancer (which can develop with estrogen-only therapy).
  • Is not needed for women who have no uterus.
  • May trigger monthly withdrawal bleeding when progestin is used periodically (such as in cyclic HRT).

Patch warning. Direct sunlight or high heat can increase, then decrease, the amount of hormone released from a patch. This can give you a big dose at the time and leave less hormone for the patch to release later in the week. Avoid direct sunlight on the hormone patch. Also avoid using a tanning bed, heating pad, electric blanket, hot tub, or sauna while you are using a hormone patch.

Why It Is Used

The estrogen in hormone therapy is used by some post-menopausal women to increase estrogen levels. This helps prevent osteoporosis and perimenopausal symptoms, such as hot flashes and sleep problems.

But HRT slightly increases risks of some serious health problems. In a small number of women, HRT may increase the risk of blood clots, stroke, heart disease, breast cancer, ovarian cancer, or dementia.2, 1 In women who are 10 or more years past menopause, using HRT slightly raises the risk of heart disease.6

Because of the risks of HRT, many experts recommend that HRT be used for:

  • Short-term treatment of menopause symptoms. HRT effectively relieves menopause symptoms for most women. Women who decide that HRT benefits outweigh their risks are advised to use the lowest effective dose for as short a time as possible.2 For most women, menopause symptoms naturally improve within a few years' time, making long-term symptom treatment unnecessary.
  • Osteoporosis prevention and treatment, in select cases. Most experts recommend that long-term HRT only be considered for women with a high osteoporosis risk. In this case, estrogen's bone-protecting benefit may outweigh the risks of taking HRT. Women are now encouraged to consider all possible osteoporosis treatments and to compare their risks and benefits.

Who should not use HRT

You should not use HRT if you:

  • Could be pregnant.
  • Have a personal history of breast cancer or ovarian cancer.
  • Have a personal history of certain endometrial cancers.
  • Have a personal history of pulmonary embolism, deep vein thrombosis, heart attack, or stroke.5
  • Have vaginal bleeding from an unknown cause.
  • Have active liver disease. You may be able to use an alternative to oral estrogen that bypasses the liver, such as estrogen delivered from a skin patch (transdermal) or vaginal cream.

How Well It Works

HRT increases estrogen levels, which may:

  • Reduce the frequency and severity of hot flashes.4
  • Improve moodiness and sleep problems related to hormone changes.2
  • Maintain the lining of the vagina, which in turn reduces irritation.
  • Increase skin collagen levels, which decline as estrogen levels decline. Collagen is responsible for the stretch in skin and muscle.
  • Help prevent postmenopausal osteoporosis by slowing bone loss and promoting some increase in bone density.4
  • Reduce the risk of dental problems, such as tooth loss and gum disease.

Side Effects

Risks of hormone replacement therapy

Hormone replacement therapy (HRT) may increase the risk of health problems in a small number of women. This increase in risk depends on your age, your personal risk, and when HRT is started.2 Talk with your doctor about these risks. Using HRT may increase your risk of:

  • Stroke.
  • Blood clots.
  • Heart disease.
  • Breast cancer.
  • Uterine (endometrial) cancer.
  • Gallstones.
  • Ovarian cancer.
  • Dementia.

Experts do not yet know whether lower-dose, shorter-term HRT reduces or eliminates these risks.

Estrogen side effects

Side effects that can occur with all forms of estrogen but are more frequent with oral estrogen include:

  • Irregular vaginal bleeding.
  • Headaches.
  • Nausea.
  • Vaginal discharge.
  • Fluid retention.
  • Weight gain.
  • Breast tenderness.
  • Spotting or darkening of the skin, particularly on the face.
  • Gallstones. Women who use estrogen replacement therapy are more likely to have gallstones that cause symptoms than women who do not use ERT. (High estrogen levels are linked to gallbladder disease.
  • In rare cases, an increased growth of pre-existing uterine fibroids or a worsening of endometriosis.

In addition, the estrogen patch (transdermal estrogen) may cause skin irritation.

Some of these side effects, such as headaches, nausea, fluid retention, weight gain, and breast tenderness, may go away after a few weeks of use.

Progestin side effects

The side effects of progestin often cause women to stop using hormone replacement therapy (HRT). Adjusting the progestin dose, changing the dosing schedule, or changing the type of progestin may reduce side effects. The progestin intrauterine device (IUD) reduces or eliminates side effects that are common with oral progestin.5

Progestin side effects include:

  • Mood changes, such as anxiety, irritability, or depression.
  • Headache.
  • Breast pain or tenderness.
  • Abdominal pain or bloating (distention).
  • Dizziness or drowsiness.
  • Diarrhea.
  • Vaginal discharge.

Cyclic progestin (taken 10 to 14 days a month) is more likely to cause:

  • Premenstrual-like symptoms, such as bloating, cramping, breast tenderness, nausea, and depression.
  • Monthly withdrawal bleeding.

The combination transdermal patch may cause skin irritation.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

If you have been taking HRT, talk with your doctor about your reasons for taking it. Are you taking it to help with perimenopausal symptoms or for long-term health reasons? Consider changing to another treatment, depending on the problem you are using HRT to treat. If HRT seems like the best choice for you, plan to use the lowest possible effective dose.

If you are unable to tolerate the side effects of progestin in hormone replacement therapy and you have not had a hysterectomy, try non-hormonal treatment options.

The British Million Women Study has confirmed the Women's Health Initiative findings and has provided more information about estrogen, progestin, and breast and endometrial cancers.3 This is important information for women deciding whether to take estrogen without progestin, as described above.

When given with a skin patch, estrogen-progestin enters the bloodstream directly, without passing through the liver. The estrogen and progestin in pills must be processed by the liver before entering the bloodstream. This is why women with liver or gallbladder disease can usually use a patch form of HRT.

Complete the new medication information form (PDF) (What is a PDF document?) to help you understand this medication.



  1. Practice Committee, American Society for Reproductive Medicine (2008). Estrogen and progestogen therapy in postmenopausal women. Educational Bulletin. Fertility and Sterility, 90(Suppl 3): S88–S102.
  2. North American Menopause Society (2010). Estrogen and progestogen use in postmenopausal women: 2010 position statement of the North American Menopause Society. Menopause, 17(2): 242–255. Also available online: http://www.menopause.org/PSht10.pdf.
  3. Million Women Study Collaborators (2003). Breast cancer and hormone-replacement therapy in the Million Women Study. Lancet, 362(9382): 419–427.
  4. Speroff L, Fritz MA (2005). Menopause and the perimenopausal transition. In Clinical Gynecologic Endocrinology and Infertility, 7th ed., pp. 621–688. Philadelphia: Lippincott Williams and Wilkins.
  5. Speroff L, Fritz MA (2005). Postmenopausal hormone therapy. Clinical Gynecologic Endocrinology and Infertility, 7th ed., pp. 689–777. Philadelphia: Lippincott Williams and Wilkins.
  6. Rossouw JE, et al. (2007). Postmenopausal hormone therapy and risk of cardiovascular disease by age and years since menopause. JAMA, 297(13): 1465–1477.


By Healthwise Staff
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Primary Medical Reviewer Brian D. O'Brien, MD - Internal Medicine
Specialist Medical Reviewer Carla J. Herman, MD, MD, MPH - Geriatric Medicine
Last Revised June 30, 2010

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.