Estradiol vs. Premarin

Hormone Therapy Drugs: Estradiol vs. Premarin


Estradiol and Premarin are two prescription hormone therapy drugs. They’re primarily used to relieve symptoms of menopause. They have the same purpose, but estradiol and Premarin differ in formulation and uses.

Comparing estradiol and Premarin

What they are and what they do

Estradiol is the most potent natural estrogen made in the body during the reproductive years. Symptoms of menopause may be caused by a natural decrease in these estrogen levels. Medical formulations of estradiol can help relieve symptoms of menopause. Estradiol may be prescribed for:

  • hot flashes
  • osteoporosis prevention (after menopause)
  • vaginal dryness
  • vaginal burning

Estradiol is also used for comfort care in serious cases of breast cancer or prostate cancer.

Premarin, on the other hand, is the brand name of a conjugated estrogen. Conjugated estrogen is also a medical formulation. It’s a mixture of several types of estrogens.

Premarin is sometimes called a conjugated equine estrogen because it’s made from horse hormones.

Premarin, like estradiol, is used to provide comfort to patients with serious forms of breast cancer or prostate cancer. It’s also used to treat the same symptoms of menopause that estradiol does. Further, it’s also sometimes prescribed for abnormal uterine bleeding.

Drug features

Both drugs come in several forms. Premarin and estradiol are both available as an intramuscular injection or oral tablet. Premarin also comes as an intravenous injection and vaginal cream. Estradiol also comes in these forms:

  • transdermal spray
  • transdermal gel
  • transdermal patch
  • vaginal ring

Several versions of estradiol are transdermal. This means that the medication is absorbed through your skin.

Read more: Drug information for Premarin »

Potential risks and side effects

You should thoroughly discuss the potential side effects of every drug you take with your doctor before using it, including estradiol or Premarin. After you start taking estradiol or Premarin, report any side effects to your doctor.

Side effects

Some common side effects of both estradiol and Premarin include:

  • abdominal pain
  • breast changes and pain
  • back pain
  • depression or mood changes
  • dizziness
  • dry mouth
  • headaches
  • high blood pressure
  • increased heart rate
  • insomnia
  • stomach upset
  • vaginal discharge

Taking Premarin may cause these additional common side effects:

  • hair loss
  • skin rashes
  • double vision
  • partial or complete vision loss

Risks and interactions

Use of either estradiol or Premarin may also increase your risk of:

Herbal supplements, over-the-counter medications, and other prescription drugs may all interact with hormone therapy. Make sure to tell your doctor if you’re taking any of these substances. Drug interactions may increase your risk of side effects and complications.

Use with other pre-existing conditions

Both estradiol and Premarin may worsen certain pre-existing medical conditions, including:

  • asthma
  • diabetes
  • high blood pressure
  • high triglycerides

Neither estradiol nor Premarin are recommended for patients who have:

  • a history of heart disease
  • undiagnosed vaginal bleeding
  • a history of blood clots (deep vein thrombosis or pulmonary embolism)
  • a history of reproductive cancer

Talk to your doctor

Because of hormone therapy, women may not have to experience the uncomfortable symptoms of menopause. The key is finding the right drug, dosage, and form.

Both estradiol and Premarin require careful monitoring. Additional progesterone treatment may be required for women who haven’t had hysterectomies. It’s important to discuss all of the hormone therapy options with your doctor. Remember to report any unusual side effects immediately.

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