Drug Interactions With Phenytoin

Certain medications -- including paroxetine, cimetidine, and carbamazepine -- may potentially cause drug interactions with phenytoin. These interactions may potentially affect the level of phenytoin in your blood, raise your risk of side effects, or decrease the effectiveness of some medicines. If phenytoin drug interactions occur, your healthcare provider may need to measure the level of phenytoin in your blood and adjust your dosage as necessary.

 

An Overview of Drug Interactions With Phenytoin

Phenytoin (Dilantin®) can potentially interact with many other medications. Some of these medicines that may lead to phenytoin interactions include:
 

 

 

 

 

  • Quinidine
  • Reserpine
  • Rifampin (Rifadin®)
  • Salicylates, such as aspirin (Ecotrin®, Bayer®, Anacin®), choline magnesium trisalicylate (Trilisate®), diflunisal (Dolobid®), and salsalate (Salflex®, Disalcid®, Amigesic®)
  • Sucralfate (Carafate®)
  • Sulfonamides ("sulfa drugs"), including sulfadiazine, sulfadoxine (Fansidar®), sulfamethoxazole (Bactrim®, Septra®), and sulfisoxazole (Gantrisin®)
  • Ticlopidine (Ticlid®)
  • Theophylline
  • Tolbutamide (Orinase®)
  • Trazodone (Desyrel®)
  • Valproic acid (Depakene®) or divalproex sodium (Depakote®, Depakote ER®)
  • Warfarin (Coumadin®, Jantoven®).
     
(Drug Interactions With Phenytoin Continued: Page 2)
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;