What is letrozole used for?

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

Can I take letrozole with food?

Yes, you can take letrozole tablets with or without food.

Does letrozole affect my bones?

Yes, letrozole may cause a decrease in bone mineral density, so your doctor might want to monitor your bone health.

What should I do if I feel dizzy while taking letrozole?

Letrozole can cause dizziness and fatigue; you should use caution when driving or using machinery.

How often do I take letrozole?

The recommended dose is one 2.5 mg tablet once daily.

Will letrozole change my cholesterol levels?

Yes, letrozole may cause an increase in your total cholesterol levels.

Is letrozole safe for children?

The safety and effectiveness of letrozole in pediatric patients have not been established.

Letrozole | CAS 112809-51-5 | HPJKCIUCZWXJDR

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Anti-cancer (Aromatase Inhibitor)

Letrozole is a non-steroidal aromatase inhibitor used to treat certain types of breast cancer in postmenopausal women. It works by lowering the amount of estrogen in the body, which helps slow or stop the growth of hormone-sensitive cancer cells.

How it worksLetrozole blocks an enzyme called aromatase. This enzyme is responsible for making estrogen in postmenopausal women; by stopping this process, the drug reduces the estrogen that can fuel certain breast cancers.

Brand names:KISQALI FEMARA CO-PACK (COPACKAGED), FEMARA

Used for

Treatment of early breast cancer in postmenopausal women.Extended treatment of early breast cancer in postmenopausal women who previously took tamoxifen.First-line treatment for advanced or metastatic breast cancer in postmenopausal women.Second-line treatment for advanced breast cancer in postmenopausal women when the disease progresses after other treatments.

Conditions

Early breast cancerAdvanced breast cancerMetastatic breast cancer

Class

Aromatase inhibitorAntineoplasticAnti-cancer (Aromatase Inhibitor)Endocrine systemSkeletal system

How to take

FormsOral tablet

RoutesOral

The standard dose is one 2.5 mg tablet taken once every day. You can take it with or without food.

Patients with liver problems (cirrhosis) may need to take the dose every other day instead of every day.

Key warnings

·Letrozole may cause a decrease in bone mineral density, so monitoring your bone health may be necessary.
·It may increase your total cholesterol levels.
·It can cause dizziness, fatigue, or sleepiness, so use caution when driving or operating machinery.
·Letrozole can cause serious harm to an unborn baby.

Do not use if

·Do not use if you are pregnant.
·Do not use if you have a known allergy to letrozole or any of its ingredients.

Side effects

Common

Hot flashesJoint pain (arthralgia)FlushingWeakness or tiredness (asthenia)Swelling (edema)HeadacheDizzinessIncreased cholesterol levelsIncreased sweatingBone pain

Serious

·Decreased bone mineral density (bone thinning)
·Increased total cholesterol
·Fetal harm if taken during pregnancy

Seek help if

·If you experience severe bone pain
·If you suspect you are pregnant
·If you experience significant dizziness or fatigue

Interactions

·Taking tamoxifen with letrozole may reduce the amount of letrozole in your blood, though taking them at different times of the day may help.
·No significant interaction was found with cimetiidine or warfarin.
·There is currently no experience using letrozole with other anti-cancer drugs.

FoodFood does not affect how letrozole is absorbed.

Special populations

PregnancyLetrozole can cause fetal harm and should not be used during pregnancy. Women of reproductive age should have a pregnancy test before starting treatment and should use effective birth control while taking this medication.

PediatricThe safety and effectiveness of letrozole in children have not been established.

GeriatricLetrozole is used in older adults; clinical studies included many patients aged 65 and older, including those over 75.

Talk to your doctor

Monitor

·Bone mineral density
·Total cholesterol levels

Questions to ask

·How will letrozole affect my bone density?
·Should I monitor my cholesterol levels while on this medication?
·What should I do if I miss a dose?
·Are there any specific foods or other medicines I should avoid?

Pharmacokinetics

Half-lifeAbout 2 days

BioavailabilityRapidly and completely absorbed from the gastrointestinal tract

MetabolismMetabolized slowly to an inactive metabolite

ExcretionMajor clearance pathway is renal (via urine); about 90% is recovered in urine

Practical

OverdoseIf an overdose occurs, medical monitoring is necessary. If the person is alert, doctors may suggest inducing vomiting.

Ingredients

Allergens

Lactose

Inactive

Colloidal silicon dioxideFerric oxide (yellow)HypromelloseLactose monohydrateMagnesium stearateMicrocrystalline cellulosePregelatinized starchPolyethylene glycolSodium starch glycolateTalcTitanium dioxide

Educational summary derived from FDA labeling, AI-assisted. Not medical advice — consult a healthcare professional. Updated 2026-04-25.