Lancet Child Adolesc Health

Two-hour observation: Is it safe for kids after anaphylaxis?

June 26, 2025

Study details: This multicenter, retrospective cohort study analyzed 5,641 pediatric patients (ages 6 months–17 years) treated with epinephrine for acute allergic reactions across 31 North American emergency departments from 2016 to 2019. The primary outcome was the time from first to last epinephrine dose, stratified by severity of initial symptoms.

Results: Only 4.7% of patients required repeat epinephrine after two hours, and just 1.9% after four hours. The cumulative incidence of repeat dosing dropped below 2% at 115 minutes overall (95% confidence interval [CI], 105-122), with variation by severity: 105 minutes for mild cases, 109 minutes for respiratory involvement, and 161 minutes for cardiovascular involvement.

Clinical impact: These findings support a shorter, risk-stratified observation period for pediatric anaphylaxis. Most children may be safely discharged after two hours, potentially reducing ED crowding and resource use. A 4-hour window may suffice for higher-risk patients with cardiovascular symptoms who are clinically stable.

Source:

Dribin TE, et al; Pediatric Emergency Medicine Collaborative Research Committee of the American Academy of Pediatrics. (2025, July). Lancet Child Adolesc Health. Timing of repeat epinephrine to inform paediatric anaphylaxis observation periods: a retrospective cohort study. https://pubmed.ncbi.nlm.nih.gov/40506197/