Background and Objective: Allergic reactions, including anaphylaxis, are rising among children. Little is known about health care utilization among infants and toddlers. Our objective was to characterize health care utilization and charges for acute allergic reactions (AAR). Methods: We conducted a retrospective cohort study of trends in emergency department (ED) visits and revisits, hospitalizations and rehospitalizations, and charges among infants and toddlers (ages < 3 years), with an index ED visit or hospitalization for AAR (including anaphylaxis). We used data from population-based multipayer data: State Emergency Department Databases and State Inpatient Databases from New York and Nebraska. Multivariable logistic regression was used to identify factors associated with ED revisits and rehospitalizations. Results: Between 2006 and 2015, infant and toddler ED visits for AAR increased from 27.8 per 10,000 population to 35.2 (Ptrend < 0.001), whereas hospitalizations for AAR remained stable (Ptrend = 0.11). In the one year after an index AAR visit, 5.1% of these patients had at least one AAR ED revisit and 5.9% had at least one AAR rehospitalization. Factors most strongly associated with AAR ED revisits included an index visit hospitalization and receipt of epinephrine. Total charges for AAR ED visits (2009-2015) and hospitalizations (2011-2015) were more than $29 million and $11 million, respectively. Total charges increased more than fourfold for both AAR ED revisits for AAR rehospitalizations during the study period. Conclusion: Infants and toddlers who presented with an AAR were at risk for ED revisits and rehospitalizations for AAR within the following year. The charges associated with these revisits were substantial and seemed to be increasing.