When administering phenytoin (Dilantin) to a child, the nurse should be aware that a toxic effect of phenytoin therapy is:

Phenytoin, an anticonvulsant, can cause severe and life-threatening hypersensitivity reactions, most notably Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). SJS is a medical emergency characterized by fever, malaise, and a painful, rapidly spreading rash with blistering of the skin and mucous membranes. This represents an acute toxic effect requiring immediate discontinuation of the drug. Nurses must educate the patient and family to report any sign of a rash immediately, as early recognition is critical to prevent progression and mortality.

B. Folate deficiency: This is a potential chronic adverse effect of long-term phenytoin therapy due to interference with folate metabolism, not an acute toxic reaction.

C. Leukopenic aplastic anemia: While phenytoin can cause severe hematologic toxicities like aplastic anemia, SJS is a more characteristic and frequently cited acute life-threatening reaction.

D. Granulocytosis and nephrosis: Phenytoin is associated with agranulocytosis (a decrease, not an increase, in granulocytes) and rare nephrotoxicity; this option is inaccurate.

1. Burchum, J. R., & Rosenthal, L. D. (2022). Lehne's pharmacology for nursing care (11th ed.). Elsevier. Chapter 23, Antiepileptic Drugs, section on Phenytoin [Dilantin], subsection on Adverse Effects, specifically notes the risk of Stevens-Johnson Syndrome (SJS) and toxic epidermal necrolysis (TEN) as rare but severe dermatologic reactions.

2. U.S. Food and Drug Administration. (2023). Highlights of Prescribing Information: DILANTIN (phenytoin sodium) extended capsules. Section 5, Warnings and Precautions, 5.3 Serious Dermatologic Reactions. The official label explicitly warns of life-threatening dermatologic reactions, including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

3. Mockenhaupt, M. (2011). The diagnosis and treatment of Stevens-Johnson syndrome and toxic epidermal necrolysis. Deutsches Ärzteblatt International, 108(45), 772–782. https://doi.org/10.3238/arztebl.2011.0772. (Table 1 lists aromatic anticonvulsants, including phenytoin, as high-risk drugs for inducing SJS/TEN).

4. Hockenberry, M. J., Wilson, D., & Rodgers, C. C. (2019). Wong's nursing care of infants and children (11th ed.). Elsevier. Chapter 28, The Child with a Neurologic Condition, section on Pharmacologic Management of Seizures, discusses the adverse effects of antiepileptic drugs, highlighting the importance of monitoring for rash with medications like phenytoin.