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Generic name: exemestane
Brand name: Aromasin
Dosage form: oral tablet
Drug classes: Aromatase inhibitors, Hormones / antineoplastics

Medically reviewed by Philip Thornton, DipPharm. Last updated on Apr 4, 2023.

What is exemestane?

Exemestane (Aromasin) is a third-generation aromatase inhibitor used to treat hormone responsive breast cancers in women who are postmenopausal - have gone through menopause.

Some breast cancer cells need the hormone estrogen to grow. Exemestane works by blocking the enzyme aromatase, which converts androgen hormones into estrogen.

In premenopausal women the main source of estrogen is the ovaries. But in postmenopausal women, the main source of estrogen is from the conversion of androstenedione and testosterone - adrenal and ovarian androgen hormones - by the enzyme aromatase.

Exemestane is an irreversible, steroidal aromatase inactivator that works by binding to and and inactivating aromatase, an effect that is known as 'suicide inhibition'. This prevents aromatase from converting androgens into estrogen and cuts of the supply of estrogen that the breast cancer cells need to grow.

Exemestane was first approved by the US Food and Drug Administration (FDA) and in 1999 and marketed under the brand name Aromasin. Aromasin tablets are still available, but generic exemestane tablets have also been available for more than a decade.

What is exemestane used for?

Exemastane is used in women who are past menopause for the treatment of:

It is not known if exemastane is safe and effective in children.

Who should not take exemestane?

Do not take exemastane if you are allergic to exemastane or any of the ingredients in exemastane. See below for a complete list of ingredients in exemastane.

What should I tell my doctor before taking exemestane?

Before you take exemastane, tell your doctor about all your medical conditions, including if you:

How should I take exemestane?

What happens if I miss a dose?

If you miss a dose of exemastane, take it as soon as you remember if it is within 12 hours of the missed dose. If it has been more than 12 hours, skip the missed dose and take your next dose at the usual time.

Dosing information

The recommended dose of exemestane is one 25mg tablet taken once a day after a meal.

See full prescribing information for further information about exemestane dosing.

What are the side effects of exemestane?

Exemastane may cause serious side effects, including:

The most common side effects of exemastane in women with early breast cancer include:

The most common side effects of exemastane in women with advanced breast cancer include:

Your doctor will do blood tests to check your vitamin D level before starting treatment with exemastane.

Exemastane may cause decreased fertility in males and females. Talk to your doctor if you have concerns about fertility.

These are not all the possible side effects of exemastane. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


Tell your doctor about all the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements.

Especially tell your doctor if you take medicines that contain estrogen, including other hormone replacement therapy or birth control pills or patches. Exemastane should not be taken with medicines that contain estrogen as they could affect how well exemastane works.

Pregnancy and breastfeeding

Tell your doctor if you are pregnant or plan to become pregnant. Taking exemastane during pregnancy or within 1 month of becoming pregnant can harm your unborn baby.

Females who are able to become pregnant should have a pregnancy test within 7 days before starting treatment with exemastane.

Females who are able to become pregnant should use effective birth control (contraceptive) during treatment with exemastane and for 1 month after your last dose of exemastane. Tell your doctor right away if you become pregnant or think you may be pregnant.

Tell your doctor if you are breastfeeding or plan to breastfeed. It is not known if exemastane passes into your breast milk. Do not breast-feed during treatment with exemastane and for 1 month after your last dose of exemastane.


What are the ingredients in exemestane?

Active ingredient: exemestane

Inactive ingredients:

Aromasin brand tablets: mannitol, crospovidone, polysorbate 80, hypromellose, colloidal silicon dioxide, microcrystalline cellulose, sodium starch glycolate, magnesium stearate, simethicone, polyethylene glycol 6000, sucrose, magnesium carbonate, titanium dioxide, methylparaben, and polyvinyl alcohol.

Algoven exemestane tablets: copovidone, crospovidone, hypromellose, magnesium stearate, mannitol, polyethylene glycol 400, silicified microcrystalline cellulose, sodium starch glycolate, and titanium dioxide.

Breckenridge Pharmaceuticals exemestane tablets: colloidal silicon dioxide, crospovidone, hydroxypropyl methylcellulose, magnesium stearate, mannitol, microcrystalline cellulose, polysorbate 80, sodium starch glycolate. The tablet coating contains hypromellose, propylene glycol, and titanium dioxide.

Cipla exemestane tablets: mannitol, crospovidone, hypromellose, polysorbate 80, microcrystalline cellulose, sodium starch glycolate, colloidal silicon dioxide, magnesium stearate. The film coating contains: hypromellose, titanium dioxide and polyethylene glycol 6000.

Aromasin brand exemestane tablets are distributed by Pharmacia & Upjohn Company LLC, a subsidiary of Pfizer Inc. New York, NY 10017.

Exemestane tablets are also distributed by Algoven, Inc, Breckenridge Pharmaceuticals, Cipla USA, Inc, and other companies. Inactive ingredients can vary depending on the distributer. For a complete list of ingredients in the tablets you take check the Product Label for your particular exemestane tablets.

Frequently asked questions

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.