Selected Anti-Aromatase Agents/Estrogens Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Very Serious. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

Anti-aromatase fight breast cancer by lowering estrogen levels. Taking estrogen may decrease the effectiveness of these medicines.

What might happen:

Your anti-aromatase agent may not work against your breast cancer.

What you should do about this interaction:

Let your healthcare professionals (e.g. doctor or pharmacist) know right away that you are taking these medicines together. Your doctor may want to change your medicines.Your healthcare professionals may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.

  • 1.Arimidex (anastrozole) Canadian prescribing information. Sanis Health Inc. July, 2015.
  • 2.Arimidex (anastrozole) UK summary of product characteristics. AstraZeneca UK Ltd July, 2011.
  • 3.Arimidex (anastrozole) US prescribing information. AstraZeneca Pharmaceuticals LP May, 2013.
  • 4.Femara (letrozole) Canadian prescribing information. Novartis Pharmaceuticals Canada Inc. April, 2014.
  • 5.Femara (letrozole) UK summary of product characteristics. Novartis Pharmaceuticals Corporation May, 2012.
  • 6.Femara (letrozole) US prescribing information. Novartis Pharmaceuticals Corporation September, 2017.
  • 7.Aromasin (exemestane) Australian prescribing information. Pharmacia Australia August 18, 2003.
  • 8.Aromasin (exemestane) Canadian prescribing information. Pfizer Canada Inc. March 01, 2005.
  • 9.Aromasin (exemestane) UK summary of product characteristics. Pharmacia Limited December 17, 2004.
  • 10.Aromasin (exemestane) US prescribing information. Pharmacia & Upjohn Company July, 2016.

Selected from data included with permission and copyrighted by First Databank, Inc. This copyrighted material has been downloaded from a licensed data provider and is not for distribution, except as may be authorized by the applicable terms of use.

CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgment of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse effects, nor should it be construed to indicate that use of a particular drug is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any drug, changing any diet or commencing or discontinuing any course of treatment.