Letrozole Dosage

Medically reviewed by Drugs.com. Last updated on May 5, 2025.

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 therapy 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 therapy 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

Renal Dose Adjustments

CrCl 10 mL/min or greater: No adjustment recommended.
CrCl less than 10 mL/min: Data not available

Liver Dose Adjustments

Mild to moderate hepatic impairment: No adjustment recommended.
Severe hepatic impairment with cirrhosis: 2.5 mg orally every other day
Noncirrhotic with elevated bilirubin: Data not available

Precautions

CONTRAINDICATIONS:

• Hypersensitivity to the active component or any of the ingredients
• Pregnancy

Safety and efficacy have not been established in patients younger than 18 years.

Consult WARNINGS section for additional precautions.

Dialysis

This drug is anticipated to be dialyzable; however, no dose adjustment guidelines have been reported.

Other Comments

Administration Advice:

• Take this drug without regard to meals.
• Use this drug only in women with clearly established postmenopausal status. In patients whose menopausal status is unclear, measure luteinizing hormone (LH), follicle-stimulating hormone (FSH) and/or estradiol levels before initiating treatment.
• Skip a missed dose if it is within 2 or 3 hours of the next dose; otherwise, take the missed dose as soon as possible and then return to the regular dosing schedule.

Storage Requirements:
Store this drug at room temperature (20 to 25 Celsius) and protect from light.

General:

• The clinical benefit of this drug in premenopausal women with breast cancer has not been determined.
• Efficacy of this drug has not been demonstrated in patients with hormone receptor negative breast cancer.
• Use of this drug in men with breast cancer has not been studied.
• Specific treatment for overdosage is not known.

Monitoring:

• Bone mineral density
• Serum cholesterol

Patient Advice:
This drug may cause fatigue, dizziness, and drowsiness; avoid driving or any other potentially dangerous activity until you know how this drug affects you.

Frequently asked questions

• How long do letrozole side effects last?
• What happens when you stop taking letrozole?
• When is the best time of day to take letrozole?
• How many cycles of letrozole are needed to get pregnant?
• Is letrozole a form of chemotherapy?
• Does letrozole affect blood sugar levels?
• When will I ovulate after taking letrozole?
• How do you take letrozole for fertility?
• How does Femara affect your period?

See also:

Further information

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

Medical Disclaimer