Phenytoin and Simvastatin Interaction
Drug interaction information between Phenytoin and Simvastatin.
Phenytoin and Simvastatin have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Phenytoin and Simvastatin. 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
Phenytoin causes your body to process simvastatin more quickly than normal. This can lower the amount of medicine available to help manage your cholesterol.
FDA Label Information
Warfarin Increased and decreased PT/INR responses have been reported when phenytoin is coadministered with warfarin Other Corticosteroids, doxycycline, estrogens, furosemide, oral contraceptives, paroxetine, quinidine, rifampin, sertraline, theophylline, and vitamin D Drugs whose level is decreased by phenytoin Antiepileptic drugs a Carbamazepine, felbamate, lamotrigine, topiramate, oxcarbazepine Antilipidemic agents Atorvastatin, fluvastatin, simvastatin Antiviral agents Efavirenz, lopinavir/ritonavir, indinavir, nelfinavir, ritonavir, saquinavir Fosamprenavir: phenytoin when given with...
Phenytoin Also Interacts With
- Nirmatrelvir/Ritonavir major
- Posaconazole major
- Ranolazine major
- Voriconazole major
- Apixaban moderate
Simvastatin Also Interacts With
- Diltiazem major
- Verapamil major
- Cyclosporine major
- Amiodarone major
- Dronedarone major
Frequently Asked Questions
What SPL severity band is on file for Phenytoin + Simvastatin?
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 Simvastatin's 41. In the minor band specifically: Phenytoin has 120 (also Atorvastatin, Omeprazole, Methylphenidate, Paroxetine); Simvastatin has 21 (also Fenofibrate, Ketoconazole, Erythromycin, Clarithromycin).
What mechanism field is on file for Phenytoin and Simvastatin?
Phenytoin causes your body to process simvastatin more quickly than normal. This can lower the amount of medicine available to help manage your cholesterol.
Simvastatin carries more major-labeled pairs than Phenytoin
SPL source-record counts only. This page's band is minor · classes on file: Phenytoin (Anticonvulsant (Hydantoin)); Simvastatin (HMG-CoA Reductase Inhibitor (Statin)).
Simvastatin has 11 major-labeled pairs vs Phenytoin's 4. 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
- Omeprazole
- Methylphenidate
- Paroxetine
11 major · 9 moderate · 21 minor · 41 total
- Other minor peers for Simvastatin
- Fenofibrate
- Ketoconazole
- Erythromycin
- Clarithromycin
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.