Letrozole and Cimetidine Interaction
Drug interaction information between Letrozole and Cimetidine.
Letrozole and Cimetidine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Letrozole and Cimetidine. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Taking cimetidine does not change the levels of letrozole in your system. There is no significant interaction between these two drugs.
FDA Label Information
Cimetidine A pharmacokinetic interaction study with cimetidine (Study P004) showed no clinically significant effect on letrozole pharmacokinetics.
Letrozole Also Interacts With
View all Letrozole interactions →Cimetidine Also Interacts With
- Levofloxacin major
- Posaconazole major
- Risperidone major
- Valproate major
- Empagliflozin moderate
Frequently Asked Questions
What SPL severity band is on file for Letrozole (Fertility) + Cimetidine?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Cimetidine has 77 labeled pairs on file vs Letrozole's 4. In the minor band specifically: Letrozole has 4 (also Warfarin, Tamoxifen, Letrozole); Cimetidine has 63 (also Albendazole, Alogliptin, Alosetron, Alprazolam).
What mechanism field is on file for Letrozole (Fertility) and Cimetidine?
Taking cimetidine does not change the levels of letrozole in your system. There is no significant interaction between these two drugs.
Cimetidine carries more major-labeled pairs than Letrozole
SPL source-record counts only. This page's band is minor · classes on file: Letrozole (Aromatase Inhibitor (Off-Label Fertility)); Cimetidine (H2 Receptor Antagonist).
Cimetidine has 4 major-labeled pairs vs Letrozole's 0. This page itself is in the minor band, not the major band.
0 major · 0 moderate · 4 minor · 4 total
4 major · 10 moderate · 63 minor · 77 total
- Other minor peers for Cimetidine
- Albendazole
- Alogliptin
- Alosetron
- Alprazolam
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.