Go Ad-Free
logoThe People's Perspective on Medicine

Conjugated estrogens


This natural estrogen formulation is one of the most commonly prescribed medicines in the country. The hormones are purified from pregnant mares' urine.

Estrogen replacement therapy is prescribed primarily to relieve menopausal symptoms such as hot flashes. It has also become a popular measure for preventing osteoporosis and reducing the risk of heart disease.

It is approved for treating breast engorgement right after childbirth when a woman does not plan to breastfeed.

Estrogen can also be helpful in various conditions where a woman does not produce enough natural estrogen. Certain cancers in men and women may benefit from estrogen therapy.

Side Effects and Interactions

Premarin has a number of potential side effects, including breakthrough menstrual bleeding, breast tenderness, bloating, nausea, vomiting, stomach pain, headache, gallbladder problems, liver tumors, depression, jaundice and high blood pressure.

Some women experience an increase in blood sugar and may go on to develop diabetes.

The skin may become more sensitive to sunburn, so it is wise to use sunscreen or wear protective clothing (including sunglasses) if you will be out in the sun.

Some kinds of vaginal infections may be more common in women using estrogen. Candida or yeast overgrowth may be a problem.

Other adverse reactions include a change in weight, fluid retention, alteration in sex drive, hair loss, and change in the curvature of the cornea. This may make contact lenses inappropriate.

Your doctor should be notified immediately of any of the following symptoms: pain in the calf or groin, sudden shortness of breath or sharp chest pain, sudden severe headache, blurred vision or speech, weakness or numbness in an arm or leg, yellow skin or eyes or severe abdominal pain.

Let your doctor know if you suspect you may have become pregnant, if you feel seriously depressed, if you notice lumps in your breast, or if vaginal bleeding is abnormal.

Premarin may interact with several other medications, such as Dilantin, Mesantoin, rifampin, or cortisone and other steroids.

The activity of the anticoagulant Coumadin and that of certain antidepressants may be altered.

Adequate calcium and vitamins B6 and folic acid are important.

Until the estrogenic activity of hops is further studied, taking this herb in combination with medicines such as oral contraceptives or hormone replacement therapy is an experiment best avoided.

In general, the herb chaste tree berry should not be combined with menopausal hormone replacement therapies.

Saw palmetto berries, which have both estrogenic and antiestrogenic activity, are not recommended for women using female hormones for hormone replacement therapy.

Check with your doctor and pharmacist before taking any other medicine or herbs while taking Premarin.

Special Precautions

There are a number of situations where Premarin may be inappropriate. Pregnant women should not use this medication, as it could affect the fetus.

Women with a history of breast cancer or other malignant disease susceptible to estrogen are generally advised to avoid this hormone.

Blood clotting disorders such as thrombophlebitis are also a reason to be wary of Premarin.

Prolonged use of postmenopausal estrogen has been controversial because of questions about cancer.

Endometrial carcinoma or cancer of the uterine lining is more of a risk for women exposed to estrogen. This adverse reaction may be counteracted by simultaneous administration of progestins.

Vaginal bleeding could be an early warning sign of cancer and requires immediate medical attention.

The risk of breast cancer is more uncertain. Studies have provided conflicting results, and more research is needed. Women with a strong family history of breast cancer will want to discuss this issue with their doctor.

Taking the Medicine

It is important to take Premarin exactly according to the doctor's instructions, since the dose and timing are different depending on the purpose for which it is being used.

Women who have menopausal symptoms but are still having menstrual cycles start taking Premarin on the fifth day of menstrual bleeding. They then take one pill daily for three weeks, and no Premarin for the following week.

Doctors often prescribe a progestin compound in addition for women who have not had a hysterectomy.

Make sure you understand the schedule of when to take Premarin and when to take the progestin.

Rate this article
5- 1 rating
About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
Tired of the ads on our website?

Now you can browse our website completely ad-free for just $5 / month. Stay up to date on breaking health news and support our work without the distraction of advertisements.

Browse our website ad-free
Join over 150,000 Subscribers at The People's Pharmacy

We're empowering you to make wise decisions about your own health, by providing you with essential health information about both medical and alternative treatment options.