Prenatal Multivitamin and Phenytoin Interaction
Drug interaction information between Prenatal Multivitamin and Phenytoin.
Prenatal Multivitamin and Phenytoin have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Prenatal Multivitamin and Phenytoin. 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
The folic acid in the vitamin speeds up how fast your body breaks down the seizure medicine. This can lower the amount of medicine in your blood and make it less effective at preventing seizures.
FDA Label Information
Drugs which may interact with folate include: • Antiepileptic drugs (AED): The AED class including, but not limited to, phenytoin, carbamazepine, primidone, valproic acid, fosphenytoin, valproate, phenobarbital and lamotrigine have been shown to impair folate absorption and increase the metabolism of circulating folate. • Additionally, concurrent use of folic acid has been associated with enhanced phenytoin metabolism, lowering the level of the AED in the blood and allowing breakthrough seizures to occur. Caution should be used when prescribing this product among patients who are receiving...
Prenatal Multivitamin Also Interacts With
- Trimethoprim moderate
- Metformin minor
- Fluoxetine minor
- Ibuprofen minor
- Potassium Chloride minor
Phenytoin Also Interacts With
- Nirmatrelvir/Ritonavir major
- Posaconazole major
- Ranolazine major
- Voriconazole major
- Apixaban moderate
Frequently Asked Questions
What SPL severity band is on file for Prenatal Multivitamin + Phenytoin?
Compiled FDA labeling labels this pair moderate. 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 Prenatal Multivitamin's 23. In the moderate band specifically: Prenatal Multivitamin has 2 (also Trimethoprim); Phenytoin has 23 (also Apixaban, Aprepitant, Canagliflozin, Carbidopa/Levodopa).
What mechanism field is on file for Prenatal Multivitamin and Phenytoin?
The folic acid in the vitamin speeds up how fast your body breaks down the seizure medicine. This can lower the amount of medicine in your blood and make it less effective at preventing seizures.
Phenytoin carries more major-labeled pairs than Prenatal Multivitamin
SPL source-record counts only. This page's band is moderate · classes on file: Prenatal Multivitamin (Prenatal Vitamin); Phenytoin (Anticonvulsant (Hydantoin)).
Phenytoin has 4 major-labeled pairs vs Prenatal Multivitamin's 0. This page itself is in the moderate band, not the major band.
0 major · 2 moderate · 21 minor · 23 total
- Other moderate peers for Prenatal Multivitamin
- Trimethoprim
4 major · 23 moderate · 120 minor · 147 total
- Other moderate peers for Phenytoin
- Apixaban
- Aprepitant
- Canagliflozin
- Carbidopa/Levodopa
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.