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Letrozole

Generic Name: letrozole (LET roe zol)
Brand Name: Femara

Medically reviewed on January 2, 2018

What is letrozole?

Letrozole lowers estrogen levels in postmenopausal women, which may slow the growth of certain types of breast tumors that need estrogen to grow in the body.

Letrozole is used to treat breast cancer in postmenopausal women. It is often given to women who have been taking tamoxifen (Nolvadex, Soltamox) for 5 years.

Letrozole may also be used for purposes not listed in this medication guide.

Important Information

You should not use letrozole if you have not gone completely through menopause, or if you are pregnant.

Before taking this medicine

You should not use letrozole if you are allergic to it, or if:

  • you have not gone completely through menopause; or

  • you are pregnant.

Although it is not likely that a postmenopausal woman would be pregnant, letrozole can harm an unborn baby. Do not use if you are pregnant or may become pregnant. Use effective birth control if you are not past menopause. Keep using birth control for at least 3 weeks after your last dose of letrozole. Tell your doctor if you think you may be pregnant.

To make sure letrozole is safe for you, tell your doctor if you have:

It is not known whether letrozole passes into breast milk or if it could harm a nursing baby. You should not breast-feed while you are using letrozole and for at least 3 weeks after your last dose.

How should I take letrozole?

Letrozole is usually taken once per day, or once every other day. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

You may take letrozole with or without food.

While using letrozole, you may need frequent blood tests. Your bone mineral density may also need to be checked.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking letrozole?

This medication may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

This medicine can pass into body fluids (urine, feces, vomit). Caregivers should wear rubber gloves while cleaning up a patient's body fluids, handling contaminated trash or laundry or changing diapers. Wash hands before and after removing gloves. Wash soiled clothing and linens separately from other laundry.

Letrozole side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Common side effects may include:

  • dizziness, drowsiness, weakness, tired feeling;

  • hot flashes, warmth in your face or chest;

  • bone pain, muscle or joint pain;

  • flushing (warmth, redness, or tingly feeling);

  • headache;

  • increased sweating; or

  • swelling, weight gain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also: Side effects (in more detail)

Letrozole dosing information

Usual Adult Dose for Breast Cancer:

2.5 mg orally once a day

Duration of Therapy:
-Adjuvant and Extended Adjuvant Settings: Optimal duration is unknown; discontinue treatment at relapse.
-Advanced Disease: Until tumor progression is evident.

Uses:
-Adjuvant treatment of postmenopausal women with hormone receptor positive early breast cancer.
-Extended adjuvant treatment of early breast cancer in postmenopausal women who have received 5 years of adjuvant tamoxifen therapy.
-First-line treatment of advanced breast cancer in postmenopausal women with hormone receptor positive or unknown locally advanced or metastatic breast cancer; second-line treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy.

Usual Adult Dose for Breast Cancer -- Adjuvant:

2.5 mg orally once a day

Duration of Therapy:
-Adjuvant and Extended Adjuvant Settings: Optimal duration is unknown; discontinue treatment at relapse.
-Advanced Disease: Until tumor progression is evident.

Uses:
-Adjuvant treatment of postmenopausal women with hormone receptor positive early breast cancer.
-Extended adjuvant treatment of early breast cancer in postmenopausal women who have received 5 years of adjuvant tamoxifen therapy.
-First-line treatment of advanced breast cancer in postmenopausal women with hormone receptor positive or unknown locally advanced or metastatic breast cancer; second-line treatment of advanced breast cancer in postmenopausal women with disease progression following antiestrogen therapy.

What other drugs will affect letrozole?

Other drugs may interact with letrozole, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

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

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