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Trade/other name(s): Aromasin

Why would this drug be used?

Exemestane is used to treat breast cancer in women who are past menopause.

How does this drug work?

Exemestane is part of a general group of drugs called aromatase inhibitors. It keeps the body from making estrogen without affecting other hormones. 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 think you might want to have children in the future. This drug has only been tested in women who have gone through menopause, and it may reduce fertility in those who have not. It may also reduce fertility if used in men. Talk with your doctor about the possible risk with this drug and the options that may preserve your ability to have children.
  • 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) may reduce the action of 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 adjust 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 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.


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.

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.


  • Tiredness (fatigue)
  • Swelling of hands, feet, or ankles

Less common

  • Hot flashes*
  • Headache
  • Pain at tumor site
  • Nausea
  • Depression*
  • Anxiety
  • Increased sweating
  • Bone or joint pain
  • Thinning hair
  • Trouble sleeping
  • Diarrhea


  • Increased appetite
  • Weight gain
  • Pain
  • High blood pressure
  • Allergic reactions*
  • Hepatitis (liver inflammation)*
  • Increased osteoporosis (bone thinning) with increased risk of broken bones

*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: 03/19/2013
Last Revised: 03/19/2013