Does Estrogens Interact with Anastrozole?
Estrogens and Anastrozole have a contraindicated drug interaction according to U.S. FDA drug labeling data. Estrogen-containing therapies should not be used with anastrozole as they may diminish its pharmacological action. The mechanism involves diminishes pharmacological action of anastrozole. Patients taking both medications should consult their healthcare provider before starting, stopping, or changing the dosage of either drug. This information is based on official FDA drug labeling sourced from OpenFDA and the NIH National Library of Medicine.
- Severity
- Contraindicated
- Anastrozole Class
- Aromatase Inhibitor
- Management
- Do not take together
- Data Source
- U.S. FDA via OpenFDA
How This Interaction Works
The interaction between Estrogens and Anastrozole occurs because diminishes pharmacological action of anastrozole. Clinically, this means estrogen-containing therapies should not be used with anastrozole as they may diminish its pharmacological action. Because of the severity of this interaction, these medications are contraindicated — meaning they should not be taken together under any circumstances. If you are currently taking both, contact your healthcare provider immediately to discuss alternatives.
What To Tell Your Doctor or Pharmacist
If you are taking Estrogens and your doctor is considering prescribing Anastrozole (or vice versa), make sure to:
- Inform your doctor and pharmacist of all current medications, including over-the-counter drugs and supplements
- Ask whether the benefits of combining these medications outweigh the risks for your specific situation
- Ask what symptoms to watch for that would indicate the interaction is causing problems
- Ask about alternative medications that do not interact with your current regimen
- Ask how frequently you should be monitored while these are co-prescribed
- Never stop or change either medication without first consulting your healthcare provider