Phenytoin lowers the
plasma levels of
mebendazole. Fosphenytoin is expected to
interact similarly.
When treating systemic worm infections it may be necessary to increase the
mebendazole dosage in patients taking
phenytoin or fosphenytoin. Monitor the
outcome of concurrent use. This interaction is of no importance when
mebendazole is used for intestinal worm infections where its action is a local effect on the worms in the gut.