Hypersensitivity and dose related side effects of phenytoin mimicking critical illness

OBJECTIVE: To describe phenytoin-induced rare hypersensitivity and dose related reactions, emphasizing the importance of early omission of drug to achieve clinical improvement. DESIGN: Case series and review of literature. SETTING: Tertiary level medical intensive care unit. PATIENTS: Three cases, two of whom had hypersensitivity reactions and the third had drug-induced dyskinesia. INTERVENTION: Omission of phenytoin and corticosteroid therapy in two cases. RESULTS: Improvement and discharge. CONCLUSION: A high index of suspicion of drug-induced complications is necessary especially when multiple drugs are being administered to critically ill patients.