Warfarin and phenytoin drug interaction with possible purple glove syndrome.

Though the impact of phenytoin on warfarin has been reported to potentiate the anticoagulant effect or interact in a biphasic manner, the effect of phenytoin on warfarin appears to be unpredictable and dependent upon multiple factors. Additionally, purple glove syndrome has rarely been reported secondary to therapeutic doses of oral phenytoin. We report on the case of a patient who experienced international normalized ratio (INR) fluctuations upon initiation of warfarin and phenytoin concurrently and who subsequently required discontinuation of therapeutic-dose phenytoin secondary to possible purple glove syndrome.