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PREMARIN (Conjugated estrogens) is an estrogen replacement drug. The tablets are used to reduce moderate to severe symptoms of menopause, including feelings of warmth in the face, neck, and chest, and the sudden intense episodes of heat and sweating known as "hot flashes." Cenestin tablets, containing a synthetic form of conjugated estrogens, may also be prescribed for these symptoms.
In addition to the symptoms of menopause, PREMARIN tablets are prescribed for teenagers who fail to mature at the usual rate, and to relieve the symptoms of certain types of cancer, including some forms of breast and prostate cancer.


Estrogens are one of the two major classes of female hormones. (Progestins comprise the second major class). Estrogens are used primarily to treat the symptoms of menopause and states in which there is a deficiency of estrogen, for example, in women who have had their ovaries removed.
PREMARIN are a mixture of several different estrogens (estrogen salts) that are derived from natural sources and blended to the approximate composition of estrogens in the urine of pregnant mares. The main components are sodium estrone sulphate and sodium equilin sulfate. Estrogens have widespread effects on many tissues in the body. Estrogens cause growth and development of the female sexual organs and maintain female sexual characteristics such as the growth of underarm and pubic hair, body contours and skeleton. Estrogens also increase secretions from the cervix and growth of the inner lining of the uterus (endometrium).

How to take

Your doctor will start therapy with PREMARIN at a low dose and adjust the dosage according to your response. He or she will want to check you periodically at 3- to 6-month intervals to determine the need for continued therapy.
Hot flashes associated with menopause
The usual starting dosage is 0.3 milligrams daily, taken continuously or in cycles such as 25 days on PREMARIN and 5 days off.
Tissue degeneration in the vagina
The usual starting dosage is 0.3 milligrams daily, taken continuously or in cycles.
Low estrogen levels due to reduced ovary function
The usual dosage is 0.3 to 0.625 milligrams daily, taken cyclically.
Ovary removal or ovarian failure
The usual dosage is 1.25 milligrams daily, taken cyclically.
Prevention of osteoporosis (loss of bone mass)
The usual starting dosage is 0.3 milligrams daily, taken continuously or in cycles.
Advanced androgen-dependent cancer of the prostate, for relief of symptoms only
The usual dosage is 1.25 to 2.5 milligrams 3 times daily.
Breast cancer (for relief of symptoms only) in appropriately selected women and men with metastatic disease
The suggested dosage is 10 milligrams 3 times daily for a period of at least 3 months. Tell your doctor if you have any unusual bleeding.

Side effects

Common side effects of conjugated estrogens include headache, abdominal pain, nervousness, nausea, back pain, joint pain and vaginal bleeding. Patients may also experience vaginal spotting, loss of periods or excessively prolonged periods, breast pain, breast enlargement and an increase or decrease in sexual drive. Effects of estrogen on the skin include rash, and melasma (tan or brown patches) that may develop on the forehead, cheeks, or temples and may persist even after estrogens are stopped. In the eyes, conjugated estrogens may cause an increase in the curvature of the cornea, and, as a result, patients with contact lenses may develop intolerance to their lenses. Estrogens may increase calcium levels in the blood (hypercalcemia) in patients with breast and bone cancer. Some patients may experience increased blood pressure and triglyceride levels.


For women who have not had a hysterectomy, the risk of endometrial and uterine cancer increases when estrogen-only drugs are used for a long time or taken in large doses. Estrogen therapy can also worsen endometriosis (uterine tissue growing outside the uterus). If you have ever had endometriosis, make sure the doctor is aware of it. If you have had a hysterectomy but still have residual endometriosis, your doctor may want you to use an estrogen/progesterone combination.
Certain studies have shown that women taking estrogen for prolonged periods of time (4 years or more) face an increased risk of breast cancer, and a study by the National Heart, Lung and Blood Institute (NHLBI) has confirmed an increased risk among women taking estrogen/progesterone combinations. Use combination products (and estrogen-only preparations, too) with special caution if you have a family history of breast cancer or have ever had an abnormal mammogram. Be sure to get an annual breast exam from your doctor, and do your own self-examination each month.
The NHLBI study also found an increased risk of dementia for women taking estrogen or estrogen/progesterone combinations.
Because PREMARIN can increase the risk of heart attack, stroke, blood clots, and certain estrogen-dependent cancers, contact your doctor right away if you notice any of the following:
Abdominal pain, tenderness, or swelling
Abnormal bleeding from the vagina
Breast lumps
Coughing up blood
Pain in your chest or calves
Severe headache, dizziness, or faintness
Sudden shortness of breath
Vision changes
Women who take PREMARIN after menopause are more likely to develop gallbladder disease.
Estrogens such as PREMARIN can cause hypercalcemia, a severe increase of calcium levels in the blood. Women with breast or bone cancer are especially at risk and should stop taking PREMARIN immediately if they develop hypercalcemia. In addition, women with the opposite problem--hypocalcemia, or a severe decrease of calcium in the blood--should use PREMARIN with caution.
Women who have not had a hysterectomy and take estrogen along with progesterone have a lower risk of precancerous endometrial changes. However, you should be aware that estrogen/progesterone combinations could increase "bad" LDL cholesterol and blood sugar levels as well as increase the risk of breast cancer.
There is a slight chance that estrogen therapy could cause an increase in blood pressure. Ask your doctor to check your blood pressure regularly.
If you have high levels of fat in your blood, specifically a high triglyceride level, conjugated estrogens such as PREMARIN are likely to cause side effects in the pancreas.
Use PREMARIN with caution if you have a history of liver problems, including jaundice. Call your doctor right away, if you develop abdominal pain or yellowing of the skin.
PREMARIN can alter thyroid function. If you are taking thyroid medication, you may need your dosage adjusted.
PREMARIN can also cause fluid retention. Use the drug with caution if you have heart or kidney problems, or any other condition that is affected by excess fluid in the body.
Some studies have shown that using estrogen-only drugs, especially for 10 years or more, could increase the risk of ovarian cancer. It is unknown whether this also applies to estrogen/progesterone combinations.
Estrogens such as PREMARIN have been known to make certain conditions worse, including asthma, diabetes, epilepsy, migraine, porphyria (a genetic enzyme deficiency), lupus, and liver tumors.
If you are using PREMARIN vaginal cream, you should be aware that this product could weaken latex condoms, diaphragms, and cervical caps.

Drug interactions

Estrogens increase the liver's ability to manufacture factors that promote the clotting of blood. Because of this, patients receiving warfarin (Coumadin), a drug that thins the blood and prevents clotting by reducing clotting factors, need to be monitored for loss of the blood thinning effect if treatment with an estrogen is begun.
Rifampin (Rifadin), barbiturates, carbamazepine (Tegretol), griseofulvin (Grifulvin), phenytoin (Dilantin), St. John's wort and primidone all increase the elimination of estrogen by enhancing the liver's ability to eliminate estrogens. Use of any of these medications with estrogens may result in a reduction of the beneficial effects of estrogens. Conversely, drugs such as erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), and ritonavir (Norvir) may reduce the elimination of estrogens by the liver as and lead to increased levels of estrogens in the blood. Grapefruit juice also may increase levels of estrogen by increasing the absorption of estrogens from the intestine. Increased levels of estrogens in the blood may result in more estrogen-related side effects.

Missed dose

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.


Store at room temperature between 59 and 86 degrees F (between 15 and 30 degrees C) away from moisture and sunlight. Do not store in the bathroom. Keep away from children and pets.