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Trade/other name(s): Aromasin

Why would this drug be used?

Exemestane is used to treat certain kinds of breast cancer in women who are past menopause. It is also being studied for other uses.

How does this drug work?

Exemestane is part of a general group of drugs called aromatase inhibitors. Normally in the body, some of the androgens (male hormones) that are made by the adrenal glands are converted to estrogen by an enzyme in fat tissue called aromatase. This drug blocks aromatase so that estrogen isn’t formed that way. This lowers estrogen levels in women who do not have functioning ovaries. This drug doesn’t affect estrogen production from the ovaries, so has little effect on estrogen levels in women whose ovaries are working. If estrogen levels are lowered, breast cancers that require estrogen to grow may stop growing or even shrink.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have any serious medical conditions, such as kidney disease or liver disease (including cirrhosis).
  • If you are still having menstrual periods. This drug is only for women who do not have functioning ovaries, such as those who are past menopause.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There is an increased risk of harm to the fetus if a woman takes this drug during pregnancy.
  • If you are breast-feeding. It is not known whether this drug passes into breast milk. If it does, it could harm the baby.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Medicines that contain estrogen (hormone therapies, birth control pills or patches) raise estrogen levels and counter the action of exemestane. These drugs should not be taken while you’re being treated with exemestane.

Some medicines and herbs can cause exemestane to be removed more quickly from the body, such as phenobarbital (Luminal), phenytoin (Dilantin), carbamazepine (Tegretol), rifampin (Rifadin), and St. John’s wort (an herbal dietary supplement). Your doctor may need to increase your exemestane dose if you are taking any of these.

Check with your doctor, nurse, or pharmacist about other medicines, vitamins, herbs, and supplements, and whether alcohol can cause problems with this medicine.

Interactions with foods

Having food in the stomach helps the drug to get into the body, so it’s best taken after a meal. No other significant interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Exemestane is given in pill form once a day after eating a meal. The dose is usually the same for all adult patients. Take this drug exactly as directed by your doctor. If you do not understand the instructions, ask your doctor or nurse to explain them to you.

Store the pills in a tightly closed container away from heat and moisture and out of the reach of children and pets.


Because this drug lowers estrogen levels, it can weaken bones and lead to a condition called osteoporosis. Bones that become weak can break (fracture) more easily.

Tell your doctor or nurse if you have severe hot flashes, trouble sleeping, or feel depressed. There is much that can be done to help with these side effects. Talk to your doctor or nurse about ways to cope with any of these problems.

It is important to keep taking this drug, even if you feel well. If you are bothered by side effects, talk to your doctor or nurse to find out if the problems are serious. Many side effects can be managed with help from your doctor.

Your doctor may do blood tests to check your vitamin D levels before you start this drug, and do other blood tests to watch your kidney and liver function.

Rarely, this drug can affect the liver. Call your doctor right away if you notice any yellowing of the skin or eyes, or any darkening of the urine.

Tell your doctor if you have rashes, itching, trouble breathing, or other possible signs of allergy.

Taking this drug during pregnancy can cause birth defects or miscarriage.

This drug is only helpful in women who do not have functioning ovaries (such as those who are past menopause). If you had your uterus removed (a hysterectomy) but still have your ovaries, blood tests of hormone levels may need to be done to see if your ovaries have stopped working (and you have truly gone through menopause).

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • Hot flashes
  • Bone or joint pain

Less common

  • Tiredness (fatigue)
  • Increased sweating
  • Headache
  • Pain at tumor site
  • Nausea
  • Depression
  • Anxiety
  • Thinning hair
  • Trouble sleeping
  • Swelling of hands, feet, or ankles
  • Trouble breathing
  • Upset stomach
  • Diarrhea


  • Increased appetite
  • Weight gain
  • Pain
  • High blood pressure
  • Allergic reactions*
  • Hepatitis (liver inflammation)*
  • Blockage of the bile duct
  • Increased osteoporosis (bone thinning) with increased risk of broken bones*
  • Carpal tunnel syndrome
  • Numbness or tingling
  • Chest pain
  • Heart failure
  • Stroke
  • Death due to stroke or heart failure

*See “Precautions” section for more detailed information

There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved in 1999.

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 08/07/2014
Last Revised: 01/29/2015