Phenytoin and Omeprazole Interaction
Drug interaction information between Phenytoin and Omeprazole.
Phenytoin and Omeprazole have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Phenytoin and Omeprazole. 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
Omeprazole can interfere with how your body breaks down phenytoin. This can cause phenytoin to build up to higher levels in your blood.
Phenytoin Also Interacts With
- Nirmatrelvir/Ritonavir major
- Posaconazole major
- Ranolazine major
- Voriconazole major
- Apixaban moderate
Omeprazole Also Interacts With
- Theophylline major
- Clarithromycin moderate
- Clopidogrel moderate
- Darunavir moderate
- Tacrolimus Topical moderate
Frequently Asked Questions
What SPL severity band is on file for Phenytoin + Omeprazole?
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?
Phenytoin has 147 labeled pairs on file vs Omeprazole's 27. In the minor band specifically: Phenytoin has 120 (also Atorvastatin, Simvastatin, Methylphenidate, Paroxetine); Omeprazole has 22 (also Aripiprazole, Atomoxetine, Brexpiprazole, Carbamazepine).
What mechanism field is on file for Phenytoin and Omeprazole?
Omeprazole can interfere with how your body breaks down phenytoin. This can cause phenytoin to build up to higher levels in your blood.
Phenytoin carries more major-labeled pairs than Omeprazole
SPL source-record counts only. This page's band is minor · classes on file: Phenytoin (Anticonvulsant (Hydantoin)); Omeprazole (Proton Pump Inhibitor (PPI)).
Phenytoin has 4 major-labeled pairs vs Omeprazole's 1. This page itself is in the minor band, not the major band.
4 major · 23 moderate · 120 minor · 147 total
- Other minor peers for Phenytoin
- Atorvastatin
- Simvastatin
- Methylphenidate
- Paroxetine
1 major · 4 moderate · 22 minor · 27 total
- Other minor peers for Omeprazole
- Aripiprazole
- Atomoxetine
- Brexpiprazole
- Carbamazepine
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.