Femara (chemical name: letrozole) is an aromatase inhibitor used to treat all stages of hormone receptor-positive breast cancer in post-menopausal women.

Femara (chemical name: letrozole) is an aromatase inhibitor used:

  • to reduce the risk of hormone receptor-positive, early-stage breast cancer coming back (recurring) in post-menopausal women after surgery

  • as a first or second treatment for advanced-stage, hormone receptor-positive breast cancer in post-menopausal women

It’s important to know that Femara should not be taken at the same time as tamoxifen.


How Femara works

Femara works by blocking the enzyme aromatase, which turns the hormone androgen into small amounts of estrogen in the body. This means less estrogen is available to stimulate the growth or hormone receptor-positive breast cancer cells.

Femara will not work on hormone receptor-negative breast cancer.


Is Femara right for you?

Femara is used to treat post-menopausal women diagnosed with either early-stage or advanced-stage, hormone receptor-positive breast cancer.

If you have cirrhosis or other liver problems, Femara may affect you more than people without liver problems. Your doctor will likely recommend that you take a lower dose of Femara.

Femara isn’t commonly used to treat pre-menopausal women.

You should not take Femara if you are breastfeeding, pregnant, trying to get pregnant, or if there is any chance that you could be pregnant. Femara may cause damage to developing embryos. You should use an effective non-hormonal type of birth control while you are taking Femara. Ask your doctor which type of non-hormonal birth control would be best for you. You should use the birth control for at least three weeks after your last dose of Femara.


What to expect during Femara treatment

Femara is a pill taken once per day. It is available as a generic medicine.

If you have been diagnosed with early-stage, hormone receptor-positive breast cancer, you could take Femara in one of two ways:

  • as the first hormonal therapy medicine after breast cancer surgery; in this case you would take Femara for five years

  • as the second hormonal therapy medicine after five years of tamoxifen; in this case,
    you would also take Femara for five years, for a total of 10 years of hormonal therapy

If you’ve been diagnosed with advanced-stage, hormone receptor-positive breast cancer, you would take Femara as long as you were getting benefits from the medicine.


Femara side effects

Like almost all breast cancer medicines, Femara can cause side effects, some of them severe.

The most common side effects of Femara are:

Other serious side effects of Femara may include:

  • Bone loss: Because Femara lowers the amount of estrogen in the body, less estrogen reaches bone cells, which can lead to bone thinning and weaking, and a higher-than-average risk of breaking a bone. If you’ve been diagnosed with osteopenia or osteoporosis, your doctor will likely monitor your bone density while you’re taking Femara.

  • High cholesterol: In some cases, Femara can increase your blood cholesterol levels. If you have high cholesterol, your doctor will likely monitor your cholesterol levels while you’re taking Femara.

  • Dizziness and fatigue: Because Femara can make you feel extremely tired or dizzy, you should be careful when driving or using machinery until you know how Femara affects you.

Research suggests that up to half of the women prescribed Femara or another hormonal therapy medicine stop taking the medicine early, in many cases because of troubling or painful side effects. Still, it’s very important to know that taking hormonal therapy for the prescribed amount of time can reduce the risk of recurrence by 50% and can reduce the risk of dying from breast cancer by about 30%.

If you’re having problematic side effects from taking Femara or another hormonal therapy medicine, talk to your doctor right away. There are steps you can take to ease some of the most common side effects:

  • medicines have been shown to reduce the number and severity of hot flashes

  • complementary and alternative therapies, such as acupuncture and mindfulness meditation, have been shown to ease pain, including joint pain

  • exercise has been shown to ease joint pain and increase bone density

You also may be able to switch to a different hormonal therapy medicine or take a different dose.


Paying for Femara

If your doctor prescribes Femara and you have problems paying for it or getting it covered by insurance, the Novartis Oncology Patient Support program may be able to help you.

Learn more about Paying for Your Care, including information on additional types of financial assistance and cost-lowering tips.


Femara (letrozole) prescribing information. Novartis. USA. Available at:

— Last updated on June 29, 2022, 3:11 PM

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