Estrogen: General information and side effects

Generic Name                   Brand Name
Chlorotrianisene TACE Capsules Conjugated Estrogens Cenestin Tablets Premarin Tablets/Vaginal Cream Dienestrol DV Vaginal Cream Ortho Dienestrol Cream Diethylstilbestrol Diethylstilbestrol Tablets Esterified Estrogens Estratab Menest Tablets Estradiol Estrace Tablets/Vaginal Cream Estraderm Transdermal System Estropipate Ogen Tablets/Vaginal Cream Ortho-Est Ethinyl Estradiol Estinyl Tablets Feminone Tablets Quinestrol Estrovis

Note that there are non PMU based substitutes for PMU-derived estrogen

Prescribed for:

Menopause symptoms (moderate to severe) and the prevention of postmenopausal osteoporosis. Estrogen drugs are also prescribed for ovarian failure, breast cancer (in selected women and men), advanced cancer of the prostate, osteoporosis, abnormal bleeding of the uterus, vaginal irritation, female castration, and Tumers syndrome. Estrogens may also be prescribed for birth control. They are effective as a "morning after" contraceptive but should only be used as an emergency treatment because of the damage they can cause to developing fetuses. There is no evidence that these drugs are effective for nervous symptoms or depression occurring during menopause: They should not be used to treat these conditions; they should be used only to replace the estrogen that is naturally absent after menopause. Premarin (Equine) contains a very large amount of this very potent form of estrogen which is one of many reasons why it should not be used.

General Information:

There are six different estrogenic substances that have been identified in women, but only 3 are actually present in large amounts: estrone, estradiol, and estriol. E-1 Estrone is the most potent of the three and is the major estrogen produced by the ovaries. E-2 17beta Estratiol is the most prevalent and is naturally modified to estrone, which is then turned into E-3 estriol, the least potent of the three. All of the Estrogens listed in this section will produce equal effects and side effects when their doses are equal, taking their various potencies into account. More potent medicines require a smaller dose to produce the same effect. E-2 is the most prevalent estrogen produced by the ovaries prior to menopause.

Estrogens should not be used during pregnancy to prevent a possible miscarriage; they don't work for this purpose and are danoerous to the fetus.

Estrogens are natural body substances with specific effects on the human body, including growth and maintenance of the female reproductive system and all female sex characteristics. They promote growth and development of all parts of the reproductive system and breasts; the affect the release of hormones from the pituitary (master) gland that controls the opening of the capillaries (the smallest blood vessels); they can cause fluid retention; they affect protein breakdown in the body; they prevent ovulation and breast engorgement in women after giving birth; and they continue in the shaping and maintenance of the skeleton through their influence on calcium in the body.

The differences between the various products lie in the specific estrogenic substances they contain. Their dose, and, in some cases, the fact that they affect one part of the body more than another. For the most part, however, estrogen products are interchangeable, as long as differences in dosage are taken into account.

Cautions and Warnings:

Estrogens have been reported to increase the risk of endometrial cancer in postmenopausal women taking them for prolonged periods of time by a factor of 4.5 to 14 times; the risk tends to depend upon the duration of treatment and the dose of the Estrogen being taken. When long-term estrogen therapy is indicated for the treatment of menopausal symptoms, the lowest effective dose should be used. Low-dose estrogens taken in a cyclic fashion (the way you take birth control pills) can reduce their risks. If you have to take an estrogen for an extended period of time, you should see your doctor at least twice a year for an assessment of your current condition and your need to continue the drug therapy.

Postmenopausal women taking estrogens have a 2 to 3 times greater chance of developing gall-bladder disease. If you are taking an estrogen product and experience recurrent, abnormal, or persistent vaginal bleeding, contact your doctor immediately. If you have active thrombophlebitis or any other disorder associated with the formation of blood clots, you probably should not take this drug. If you feel that you have a disorder associated with blood clots, and you are taking an estrogen or a similar product, contact your doctor immediately.

Estrogens have been used to treat painful breast engorgement with milk that sometimes develops after giving birth. This condition usually responds to pain relievers and other treatments, and their use in this situation should be weighed against the possible embolism problem that is associited with large single estrogen doses.

Animal studies have shown that prolonged continuous administration of estrogen substances can increase the frequency of cancer (breast, cervix, vagina, kidney, and liver) in these animals, and there is evidence that these drugs may increase the risk of various cancers in humans. They shound be taken with caution by women with a strong family history of breast cancer and by those who have breast nodules fibrorystic disease of the breast, or abnormal mammograms.

It is possible that women taking Estrogens for extended periods of time may experience some of the same long-term side effects as women who have taken oral contraceptives for extended periods of time. These long-term problems may include the development of blood-clotting disorders, liver cancer or other liver tumors, high blood pressure, glucose intolerance (symptoms similar to diabetes) or worsening of the disease in diabetic patients, unusual sensitivity to the sun, and high blood levels of calcium.

Vaginal estrogen creams may stimulate bleeding of the uterus. They can also cause breast tenderness. Vaginal discharge, and withdrawal bleeding (if the product is suddenly stopped). Women with endometriosis may experience heavy vaginsl bleeding.


Estrogen products should never be used during pregnancy*. If used during the earlier stages of pregnancy, estrogens can seriously damage a developing fetus. Estrogens may reduce the flow of breast milk. The effects of estrogens on nursing infants are not predictable. Either avoid the drug while breast-feeding or bottle-feed your baby.

*Addendum submitted by Katy Giller, R.N.: According to Briggs, Freeman and Yaffe, authors of "Drugs in Lactation", 1993, estrogens are compatible with breastfeeding. While it is, of course, better to avoid them while breastfeeding, the benefits of breastfeeding far outweigh the risks. In addition, the risks involved with feeding formula, a "chemical soup", to a baby are greater than breastfeeding when the mother is taking estrogen.


Estrogens may be taken without special precaution by most seniors, but the risk of some side effects increases with age, especially if you smoke.

Possible Side Effects:

The most common side effects include enlargement or tenderness of the breasts (both sexes), swelling of the ankles and legs, loss of appetite, weight changes, retention of water, nausea, vomiting, abdominal cramps, and feeling of bloatedness. The estrogen patch can cause skin rash, irritation, and redness at the patch site.

Less common side effects are bleeding gums, breakthrough vaginal bleeding, vaginal spotting, changes in menstrual flow, painful menstruation. pre-menstrual syndrome, no menstrual period during and after estrogen use, enlargement of uterine fibroids, vaginal infection with Candida, a cystitis-like syndrome, mild diarrhea, jaundice or yellowing of the skin or whites of the eyes, rash, loss of scalp hair, and development of new hairy areas. Lesions of the eye and contact-lens intolerance have also been associated with estrogen therapy. You may experience migraine headache, mild dizziness, depression, and increased sex drive (women) or decreased sex drive (men).

Rare side effects include stroke, blood-clot formation, dribbling or sudden passage of urine, loss of coordination, chest pains, leg pains, difficulty breathing, slurred speech, and vision changes. Men who receive large estrogen doses as part of the treatment for prostate cancer are at a greater risk for heart attack, phlebitis, and blood clots in the lungs.

Drug Interactions:

Phenytoin, Ethotoin, and Mephenytoin may interfere with estrogen effects. Estrogens may reduce your requirement for oral anticoagulant (blood-thinning) drugs, an adjustment your doctor can make after a simple blood test.

Estrogens increase the amount of calcium absorbed from the stomach. This interaction is used to help women with osteoporosis to increase their calcium levels.

Estrogens may increase the side effects of antidepressants and phenothiazine tranquilizers. Low estrogen doses may increase phenothiazine effectiveness.

Estrogens may increase the amount of Cyclosporine and adrenal corticosteroid drugs in your blood. Dosage adjustments of the non-estrogen drugs may be needed.

Estrogen increases the toxic effects of other drugs on the liver, especially in women over 35 and people with preexisting liver disease.

Rifampin, barbiturates, and other drugs that stimulate the liver to break down drugs may reduce the amount of estrogen in the blood.

Estrogens may interfere with the actions of Tamoxifen and Bromocriptine.

Women, especially those over 35, who smoke cigarettes and take an Estrogen have a much greater chance of developing stroke, hardening of the arteries, or blood clots in the lungs. The risk increases as age and tobacco use increase.

Estrogens interfere with many diagnostic tests. Make sure your doctor knows that you are taking an estrogen before doing any blood tests or other diagnostic procedures.

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