What Is Aromasin® (exemestane)?

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Aromasin® (exemestane) is a type of hormone therapy for advanced or metastatic (cancer that has spread) breast cancer. It is used in women who are past menopause who experienced disease progression after treatment with tamoxifen.1,2

Aromasin is also approved to treat early breast cancer in women who are past menopause. It is used for those who have:1,2

  • Estrogen-receptor positive (ER+) early breast cancer, and
  • Have had other treatments for breast cancer, and
  • Have taken tamoxifen for 2 to 3 years, and
  • Are switching to Aromasin to complete 5 years in a row of hormone therapy

There are several generic versions of this medicine available under the name exemestane tablets.

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What are the ingredients in Aromasin?

The active ingredient in Aromasin is exemestane.1

How does exemestane work?

Breast cancers are defined as hormone receptor-positive (HR+) if they have hormone receptors on the surface of their cells. In HR+ breast cancers, hormones like estrogen can bind to the receptors. This stimulates the cancer cell’s growth.1

In women past menopause, estrogens are created when androgens are converted to estrone and estradiol by the enzyme aromatase. Exemestane is an aromatase inhibitor. It helps block the action of aromatase. This lowers the levels of estrogen in the body, which slows or stops the growth of the cancer.1

What are the possible side effects of exemestane?

The most common side effects of exemestane, depending on the specific form of breast cancer being treated, include:1

  • Hot flushes
  • Nausea
  • Fatigue
  • Increased sweating
  • Increased appetite
  • Joint pain
  • Trouble sleeping
  • Headach

Exemestane may also cause bone loss. This may increase your risk for bone fractures or weak and brittle bones (osteoporosis). Your doctor may check your bones during treatment with exemestane.1,2

These are not all the possible side effects of exemestane. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with exemestane.

Other things to know

Before taking exemestane, tell your doctor if you:1,2

  • Are not past menopause
  • Have weak or brittle bones
  • Have liver or kidney problems

Exemestane can harm an unborn baby. If you can become pregnant, you should use birth control during treatment and for some time after the last dose of exemestane. You should also not breastfeed during treatment with exemestane and for some time after the last dose. Talk to your doctor about your options for birth control and breastfeeding while taking exemestane.1,2

Before beginning treatment for breast cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.

For more information, read the full prescribing information of exemestane.