Letrozole

Name: Letrozole Drug Interactions
Creator: Dr. Brian Staiger, PharmD, BCPS

20 interactions 124 cited references

Also sold as: Femara Femara®

About Letrozole

Letrozole is a nonsteroidal aromatase inhibitor used to treat breast cancer in postmenopausal women. Read the full Letrozole drug information page →

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated Aug 10, 2026 · Editorial policy · Data sources

Sources: FDA prescribing information (Structured Product Labeling), the published literature cited in each entry, DDInter 2.0 (a major open-access drug-interaction database), and legacy DrugBank interaction data distributed by the NIH's RxNav service (decommissioned in 2024) — analyzed and reviewed by our pharmacist team. How we build this library →

Most serious with: Yellow Fever Vaccine Smallpox Monkeypox Vaccine Bacillus Of Calmette And Guerin Vaccine, Live Rubella Virus Vaccine, Live Mumps Virus Vaccine, Live Measles Virus Vaccine, Live

9 Contraindicated 9 Major 2 Moderate

All (20) Contraindicated (9) Major (9) Moderate (2)

Moderate

Letrozole Ketoconazole Topical Extina® Foam Increased letrozole plasma concentrations Details Letrozole Ketoconazole Extina Increased letrozole plasma concentrations Details

Check another drug

Still have questions about this combination?

Every question gets a real answer from a licensed pharmacist — free, and usually within a day.

Ask the pharmacist

Educational information only, not medical advice. Always confirm interactions with your pharmacist or prescriber before making any change to your medications.