Letrozole

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 →

Dr. Brian Staiger, PharmD, BCPS
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)

Contraindicated

Letrozole Bacillus Of Calmette And Guerin Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Dengue Tetravalent Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Measles Virus Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Mumps Virus Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Rubella Virus Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Smallpox Monkeypox Vaccine An increased risk of infection by the live vaccine Details Letrozole Typhoid Vaccine Typhim VI® An increased risk of infection by the live vaccine Details Letrozole Varicella Virus Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Yellow Fever Vaccine Stamaril An increased risk of infection by the live vaccine Details

Major

Letrozole Adenovirus Vaccine Type 4, Live An increased risk of infection by the live vaccine Details Letrozole Adenovirus Vaccine Type 7, Live An increased risk of infection by the live vaccine Details Letrozole Ceritinib Zykadia Increased CYP3A substrate exposure Details Letrozole Cholera Vaccine Ipol An increased risk of infection by the live vaccine Details Letrozole Cilostazol Pletal® Increased cilostazol exposure Details Letrozole Ebola Zaire Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Influenza Virus Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Rotavirus Vaccine, Live An increased risk of infection by the live vaccine Details Letrozole Tegafur Decreased exposure of 5-fluorouracil Details

Moderate

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

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