Phenytoin (diphenylhydantoin) is a widely prescribed antiepileptic drug and remains the most frequently used first-line antiepileptic drug in hospitalized patients.
1,2 Although effective for treating neurological diseases, phenytoin can cause cutaneous adverse reactions ranging from mild rash (maculopapular exanthema) to life-threatening severe cutaneous adverse reactions.
3-6 Phenytoin-related severe cutaneous adverse reactions include drug reactions with eosinophilia and systemic symptoms (DRESS), Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN).
4-6 Stevens-Johnson syndrome and TEN are variants of the same mucocutaneous blistering reaction disease and carry high morbidity and mortality (10%-50%).
4-6 DRESS, also known as drug-induced hypersensitivity syndrome, is characterized by generalized maculopapular eruptions, high fever, eosinophilia, atypical lymphocytes, and visceral involvement and has a mortality rate of approximately 10%.
6,7 Phenytoin-related severe cutaneous adverse reactions frequently impair the internal organs, leading to the highest mortality among the different antiepileptic drug–related cutaneous reactions.
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