letrozole (fertility)

Name: letrozole (fertility) — FDA Drug Safety & Adverse Event Data
Creator: PlainMeds
License: https://creativecommons.org/publicdomain/zero/1.0/

Reviewed byPlainmeds Editorial, Drug Information Editorial Team · June 5, 2026

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Brand names: Femara

Aromatase Inhibitor (Off-Label Fertility) Rx

Letrozole (Femara) is a medicine that lowers estrogen levels in women after menopause. It is used to treat certain types of breast cancer.

Drug Pricing (NADAC)

Brand Price

$25.64/unit

Generic Available

Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →

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What it does

Letrozole is used to treat breast cancer in women who have gone through menopause.

Common side effects

Hot flashes, Joint pain, Flushing

Key warnings

Letrozole can cause thinning of your bones, so your doctor may monitor your bone density.

How It Works

Letrozole belongs to a class of drugs called aromatase inhibitors. It works by blocking an enzyme called aromatase, which the body uses to make estrogen. By lowering estrogen levels, letrozole can help slow or stop the growth of breast cancer cells that need estrogen to grow.

How to Take It

Take one 2.5 mg letrozole tablet once a day. You can take it with or without food. If you have liver problems (cirrhosis), your doctor may prescribe 2.5 mg every other day. Continue taking letrozole as long as your doctor tells you to, even if you feel well.

Pregnancy & Breastfeeding

Do not take letrozole if you are pregnant. It can harm your unborn baby. Do not breastfeed while taking letrozole, as it is not known if the drug passes into breast milk.

Missed Dose

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.

Storage

Store letrozole tablets at room temperature, between 68°F and 77°F.

Serious Warnings

Letrozole can cause thinning of your bones, so your doctor may monitor your bone density. It can also increase your cholesterol levels, so your doctor may check your cholesterol. Letrozole can cause harm to an unborn baby. If you are able to become pregnant, you should have a pregnancy test before starting letrozole and use effective birth control while taking it.

Known Drug Interactions

minor warfarin

Warfarin An interaction study (P017) with warfarin showed no clinically significant effect of letrozole on warfarin pharmacokinetics.

Mechanism: Letrozole does not interfere with how the body processes warfarin. This means the blood-thinning effects of warfarin should stay the same.

What to do: You can take these medications together as prescribed without needing to change your dosage.

minor cimetidine

Cimetidine A pharmacokinetic interaction study with cimetidine (Study P004) showed no clinically significant effect on letrozole pharmacokinetics.

Mechanism: Taking cimetidine does not change the levels of letrozole in your system. There is no significant interaction between these two drugs.

What to do: No dosage adjustments are necessary when using these medications at the same time.

minor tamoxifen

7 DRUG INTERACTIONS Tamoxifen Coadministration of Femara and tamoxifen 20 mg daily resulted in a reduction of letrozole plasma levels of 38% on average (Study P015). Clinical experience in the second-line breast cancer trials (AR/BC2 and AR/BC3) indicates that the therapeutic effect of Femara therapy is not impaired if Femara is administered immediately after tamoxifen.

Mechanism: Taking tamoxifen can lower the amount of letrozole in the blood by an average of 38 percent.

What to do: Your doctor may monitor your progress, but the drugs can be used one after the other without losing effectiveness.

minor letrozole

Mechanism: Cimetidine does not have a meaningful effect on how letrozole is processed or used by the body.

What to do: No special changes or dosage adjustments are needed when taking these two medications together.

Common Questions

What if I experience fatigue or dizziness while taking letrozole?

Be careful when driving or operating machinery until you know how letrozole affects you.

Can letrozole affect my bones?

Yes, letrozole can decrease bone mineral density, potentially leading to osteoporosis and fractures.

Will letrozole interact with other medications I'm taking?

Letrozole can interact with tamoxifen, potentially reducing letrozole's effectiveness. Discuss all medications with your doctor.

How long should I take letrozole?

The duration of treatment depends on the specific situation, such as adjuvant or extended adjuvant therapy. Follow your doctor's instructions.

What should I do if I experience severe side effects?

Contact your doctor immediately if you experience severe side effects, such as chest pain, shortness of breath, or signs of an allergic reaction.

Can men take letrozole?

Letrozole is primarily used in postmenopausal women. Its use in men is not a standard indication.

Does letrozole cause weight gain?

Weight increase has been reported as a side effect in some patients taking letrozole.

Can I drink alcohol while taking letrozole?

There are no specific contraindications regarding alcohol consumption while taking letrozole, but it's best to discuss this with your doctor.

What are the inactive ingredients in letrozole tablets?

Inactive ingredients include colloidal silicon dioxide, ferric oxide, hydroxypropyl methylcellulose, lactose monohydrate, and others.

How does letrozole compare to tamoxifen?

Both drugs treat breast cancer, but letrozole lowers estrogen levels while tamoxifen blocks estrogen's effects. They have different side effect profiles.

What are the common side effects of letrozole (fertility)?

The most commonly reported side effects of letrozole (fertility) include Hot flashes, Joint pain, Flushing, Weakness, Swelling. Always consult your healthcare provider about potential side effects.

Does letrozole (fertility) interact with other medications?

Yes, letrozole (fertility) has 4 known drug interactions. Notable interactions include warfarin, cimetidine, tamoxifen. Always inform your doctor about all medications you are taking.

What drug class is letrozole (fertility)?

letrozole (fertility) belongs to the Aromatase Inhibitor (Off-Label Fertility) drug class. It requires a prescription (Rx). Letrozole is used to treat breast cancer in women who have gone through menopause.

Is letrozole (fertility) safe during pregnancy?

Do not take letrozole if you are pregnant. It can harm your unborn baby. Always consult your healthcare provider before using any medication during pregnancy or breastfeeding.

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