OBJECTIVES: The administration of 1 to 2 doses of intravenous (IV) antibiotics in the emergency department (ED) followed by discharge on oral antibiotics has become a treatment option for children with cellulitis, despite an absence of evidence supporting this practice. The objective of this study was to determine the failure rate of ED short-course IV antibiotic therapy (IV-short course). METHODS: This retrospective study included children aged 0 to 18 years diagnosed with cellulitis in a pediatric ED during the 2005 calendar year. Treatment was categorized as (a) discharge on outpatient oral antibiotics, (b) IV-short course, or (c) admission for IV antibiotics (IV-admit). Failure was defined by a subsequent visit less than 7 days since the index visit with a change in antibiotic treatment, the administration of IV antibiotics, or hospitalization. A second data abstractor reviewed 10% of the charts to allow calculation of interobserver scores. RESULTS: There were 321 eligible children, of whom 154 children were treated with oral antibiotics, 85 IV-short course, and 82 IV-admit. A total of 23 patients (7%) met criteria for failure. Compared with IV-admit, the odds ratio of failure among those who received IV-short course was 7.2 (95% confidence interval [CI], 1.6-33.1). Those who received IV-short course were more likely to revisit within 7 days than were children treated with oral antibiotics alone (risk ratio, 2.4; 95% CI, 1.2-4.7); however, revisits were no more frequent than among children in the IV-admit group (risk ratio, 2.8; 95% CI, 0.65-12.1). The total mean duration of hospital stay was significantly less in the IV-short course group compared with the IV-admit group (14.9 vs 118.6 hours; P < 0.001). CONCLUSIONS: Children with cellulitis frequently receive IV antibiotics. Short-course IV antibiotic therapy is associated with a high failure rate and prolonged ED stay compared with those in children treated with oral antibiotics alone. However, their clinical similarity to the IV-admit group, shorter length of hospital stay, but high failure rate mandates further evaluation before widespread adoption.