Background:Acute agitation in the pediatric emergency department (ED) has the potential to escalate into aggression and result in harm. Rapid and effective management may be warranted. Use of pro re nata (prn) oral immediate-release (IR) quetiapine, haloperidol, loxapine, and chlorpromazine has been observed in the pediatric ED at Surrey Memorial Hospital to manage this condition; however, evidence for oral prn antipsychotic use is limited in the pediatric population. Objectives:The primary objective is to characterize the dose of prn oral IR quetiapine used to manage acute agitation or aggression in a pediatric ED. Secondary objectives include characterizing the dose of prn oral IR haloperidol, loxapine, and chlorpromazine; and describing the 1-hour response rate, admission rate, length of stay (LOS), and adverse drug effects. Method:The medical records of pediatric patients who received at least one prn oral dose of IR quetiapine, haloperidol, loxapine, or chlorpromazine for acute agitation and aggression, without regard to the etiology of symptom presentation, between January 1, 2012 and December 31, 2016, were analyzed retrospectively. Results:Sixty-nine patients met the inclusion criteria. The mean dose of quetiapine was 32 mg/dose (0.54 mg/kg per dose); and the response rate was 53%. The mean haloperidol, loxapine, and chlorpromazine doses were 4 mg (0.07 mg/kg per dose), 13 mg (0.19 mg/kg per dose), and 29 mg/dose (0.53 mg/kg per dose) respectively; and the response rates were 36%, 30%, and 50%, respectively. Between 19% and 60% of patients were admitted, majority to the psychiatry ward. The median LOS in the ED was between 5 and 18 hours for nonadmitted patients. Extrapyramidal side effects (EPS) were reported with first-generation antipsychotics (FGA), but not with quetiapine. Conclusion:Quetiapine appears to be a viable agent for managing acute agitation and aggression in the pediatric ED with low rates of EPS. Further studies are encouraged to compare the effectiveness of quetiapine with FGA. A Clinical Trial Registration number is not applicable for this study.