Prescription medication · Aromatase Inhibitor (Off-Label Fertility)

letrozole (fertility)

Also sold as Femara. Letrozole is used to treat breast cancer in women who have gone through menopause.

Data updated 2026-05-15

4
InteractionsFew interactions
$25.64
Brand price (NADAC)

letrozole (fertility) (Femara) is a prescription Aromatase Inhibitor (Off-Label Fertility). Letrozole is used to treat breast cancer in women who have gone through menopause.

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

Verify with FDA → · CMS NADAC pricing →

Drug Pricing (NADAC)

Brand Price

$25.64/unit

Generic Available

No

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

Compare with Another Drug →

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.

The sections below are summarized in plain English from letrozole (fertility)'s FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

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.

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.

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.

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.

minor letrozole

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

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

This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.

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.
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 registry lists Hot flashes, Joint pain, Flushing, Weakness, Swelling among the most-reported FAERS reaction terms for letrozole (fertility). These counts are not an individual symptom assessment.
Does letrozole (fertility) interact with other medications?
The registry has 4 documented interaction rows for letrozole (fertility). Notable source-record pairings include warfarin, cimetidine, tamoxifen. These rows are not a complete medication review.
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.
What pregnancy or breastfeeding source fields are listed for letrozole (fertility)?
The FDA label for letrozole (fertility) contains product-specific pregnancy or breastfeeding language. PlainMeds does not apply that source text to an individual.

Related Medications in Aromatase Inhibitor (Off-Label Fertility)

Other drugs grouped near letrozole (fertility) - same-class peers and common alternatives.

abiraterone

Zytiga

Abiraterone (Zytiga) is a medicine used with prednisone to treat prostate cancer that has spread.

Compare with letrozole (fertility) →

anastrozole

Arimidex

Anastrozole is a medicine used to treat breast cancer in women after menopause.

Compare with letrozole (fertility) →

bazedoxifene/conjugated estrogens

Duavee

Duavee is a combination medicine containing estrogen and a drug that blocks estrogen in some parts of the body.

Compare with letrozole (fertility) →

cabergoline

Dostinex

Cabergoline is a medicine that helps lower the amount of prolactin in your body.

Compare with letrozole (fertility) →

clomiphene

Clomid, Serophene

Clomiphene citrate is a medicine that helps women ovulate.

Compare with letrozole (fertility) →

Compare letrozole (fertility) vs abiraterone side-by-side →

Medication Guides

Understanding Drug Interactions

How CYP450 enzymes, inhibitors, and inducers affect your medications

Generic vs Brand Name Drugs

FDA requirements, cost savings, and when the difference matters

Narrow Therapeutic Index Drugs

FDA bioequivalence and label-record context for narrow therapeutic index medicines

Common Drug Interactions

Dangerous medication combinations and how to protect yourself

Save on letrozole (fertility)

Compare prices and find discounts at pharmacies near you. Free coupons can save up to 80% on prescriptions.

Check Prices on GoodRx →

Disclosure: This link may earn us a commission at no extra cost to you. See our terms.

What the FDA Data Shows for letrozole (fertility)

The FDA label for letrozole (fertility) (sold under brand names such as Femara) classifies it as a prescription-only medication in the Aromatase Inhibitor (Off-Label Fertility) class. Letrozole is used to treat breast cancer in women who have gone through menopause. Official labeling lists 11 commonly reported side effects, including Hot flashes, Joint pain, Flushing.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. Voluntary reports accumulate over the lifetime of a drug and reflect wide-ranging clinical use. The database also lists 4 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS.

Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.

Last updated: August 21, 2025

PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.

Read our methodology - how this data is sourced, computed, and verified.

Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.

All federal data sources used on this page