Safety Profile of Low-Dose Risperidone in Critically Ill Children: A Single-Center Retrospective Cohort Study Across General and Cardiac Pediatric Intensive Care Units

Purpose To evaluate the safety profile of low-dose risperidone in critically ill children treated within an institutional multimodal delirium prevention and treatment pathway across general and cardiac pediatric intensive care units (PICU and PCICU). Methods Single-center retrospective cohort study of all patients younger than 18 years who received at least one dose of risperidone during a PICU or PCICU admission (January 2015–January 2026). Safety endpoints included corrected QT interval (QTc) change, de novo QTc > 500 ms, hepatic, renal, electrolyte, glucose and thyroid parameters, and neurological adverse events. Paired pre/post comparisons used the Wilcoxon signed-rank test. Results A total of 352 patients received risperidone across 7,970 administrations. Median age was 2.8 years (interquartile range [IQR] 0.4–11.2); 35.8% were infants younger than one year. Median dose per administration was 0.19 mg (IQR 0.10–0.37), corresponding to 0.019 mg/kg. Laboratory parameters showed no clinically meaningful hepatotoxicity, renal deterioration, electrolyte instability, or dysglycemia. Paired electrocardiogram data were available for 57 patients (16.2%); no significant QTc change was observed (median ΔQTc + 3.0 ms; p = 0.976). De novo QTc prolongation beyond 500 ms occurred in 1 of 57 patients (1.8%). In-hospital mortality was 14.5%. Conclusion Within a structured delirium pathway, low-dose risperidone was not associated with a detectable QTc or laboratory safety signal across general and cardiac pediatric ICU settings, including infants younger than one year. Prospective validation with protocolized monitoring and systematic adverse-event adjudication is required.