Estrogen Therapy (ET)

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Estrogen Therapy (ET)


Oral (pills or tablets)

Generic NameBrand Name
conjugated estrogensCenestin, Enjuvia, Premarin

Enjuvia contains plant-based, rather than animal-based, estrogen. Risks and benefits are thought to be the same for both types of estrogen.

Generic NameBrand Name
esterified estrogensMenest
estropipateOgen, Ortho-Est

Transdermal (patch placed on the skin that releases estrogen continuously)

Generic NameBrand Name
estradiolAlora, Estraderm, Vivelle-Dot

Vaginal ring (inserted high into the vagina; releases estrogen continuously for 3 months)

Generic NameBrand Name

Skin cream (applied daily to the legs, thighs, or calves)

Generic NameBrand Name

Skin gel (applied daily to an arm from wrist to shoulder)

Generic NameBrand Name

How It Works

Estrogen therapy (ET) increases the estrogen level in your body. Estrogen impacts multiple systems of the body.

When given through an estrogen patch, vaginal ring, or skin cream or gel (transdermal estrogen), estrogen enters the bloodstream directly, without passing through the liver. The estrogen in pills must be processed by the liver before entering the bloodstream, which puts stress on an impaired liver.

Low-dose vaginal estrogen affects only the urinary and genital area. For more information, see Low-Dose Vaginal Estrogen for Dryness and Atrophy.

Why It Is Used

Estrogen therapy (ET) is used to increase estrogen levels in postmenopausal women who have no uterus. This treatment may help prevent perimenopausal symptoms, osteoporosis, and colon cancer.

Women in their 20s, 30s, and 40s who experience early menopause after having their ovaries removed (oophorectomy) or because of other medical reasons typically take ET to reduce their risk of early bone loss and osteoporosis. Historically, women have continued using ET for years beyond menopause. Some women now discontinue ET around the age of menopause.

Women with a uterus who take estrogen also need the hormone progestin to prevent the estrogen from overgrowing the uterine lining, which can lead to endometrial (uterine) cancer. Estrogen-progestin is called hormone therapy (HT).

Do not use estrogen treatment if you:

  • Are pregnant.
  • Have unexplained vaginal bleeding.
  • Have active liver disease or chronic impaired liver function. (Transdermal estrogen does not stress the liver.)
  • Have a personal history of breast cancer, ovarian cancer, or endometrial cancer.
  • Are a smoker.
  • Have a history of blood clots.
  • Have had a stroke.

Talk to your doctor about your risks versus benefits if you have a family history of breast cancer, ovarian cancer, stroke, blood clots, or endometrial cancer.

How Well It Works

Systemic estrogen therapy (ET) affects your entire body and reverses the effect of low estrogen. Systemic ET may:

  • Reduce the frequency and severity of hot flashes.1
  • Improve moodiness and sleep problems related to hormone changes.2
  • Maintain the lining of the vagina, reducing 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.1
  • Reduce the risk of dental problems, such as tooth loss and gum disease.

Low-dose estrogen. Researchers are studying the effects of low-dose estrogen therapy. Low-dose estrogen may keep bones strong and may relieve hot flash symptoms.3 But the long-term risks of taking low-dose estrogen are not yet known.

Side Effects

Side effects that can occur with all forms of estrogen but are more common with oral estrogen (and less common with a patch, cream, gel, or vaginal ring) include:

  • Headaches.
  • Nausea.
  • Vaginal discharge.
  • Fluid retention.
  • Weight gain.
  • Breast tenderness.
  • Spotting or darkening of the skin, particularly on the face.
  • In rare cases, an increased growth of preexisting uterine fibroids or a worsening of endometriosis.

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.

The estrogen patch (transdermal estrogen) may cause skin irritation.

An estrogen ring must be replaced every 3 months. If the ring falls out at any time during the 3-month treatment period, you may rinse it with lukewarm water and reinsert it.

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

What To Think About

Risks of estrogen therapy

Estrogen therapy (ET) 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 ET is started.2 Talk with your doctor about these risks. Using ET may increase your risk of:

  • Stroke.
  • Blood clots.
  • Gallstones.
  • Ovarian cancer.
  • Dementia.
  • Urinary incontinence.

If you are taking ET after early menopause caused by a surgical hysterectomy, talk with your doctor about long-term ET risks and benefits.

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.

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



  1. Fritz MA, Speroff L (2011). Menopause and perimenopausal transition. In Clinical Gynecologic Endocrinology and Infertility, 8th ed., pp. 673–748. Philadelphia: Lippincott Williams and Wilkins.
  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:
  3. Fritz MA, Speroff L (2011). Postmenopausal hormone therapy. In Clinical Gynecologic Endocrinology and Infertility, 8th ed., pp. 749–857. Philadelphia: Lippincott Williams and Wilkins.


ByHealthwise Staff
Primary Medical ReviewerAnne C. Poinier, MD - Internal Medicine
Specialist Medical ReviewerCarla J. Herman, MD, MPH - Geriatric Medicine
Last RevisedAugust 8, 2012

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