BACKGROUND: Initial propranolol recommendations for infantile hemangioma published in 2013 were intended as provisional best practices to be updated as evidence-based data emerged. METHODS: A retrospective multicenter study was performed to evaluate utility of prolonged monitoring after first propranolol dose and escalation(s). Inclusion criteria included diagnosis of hemangioma requiring propranolol of ≥0.3 mg/kg/dose, age <2 years, and heart rate (HR) monitoring for ≥1 hour. Data collected included demographics, dose, vital signs and adverse events. RESULTS: 783 subjects met inclusion criteria; median age at initiation was 112 days. None of the 1148 episodes of prolonged monitoring warranted immediate intervention or drug discontinuation. No symptomatic bradycardia or hypotension occurred during monitoring. Mean HR change from baseline to 1 hour was -8.19 +/- 15.54 and baseline to 2 hours was -9.24 +/- 15.84 bpm. Three preterm subjects had dose adjustments due to prescriber concerns about asymptomatic vital sign changes. No significant difference existed in pre-treatment HR or in HR change between those with later adverse events during treatment and those without. CONCLUSION: Prolonged monitoring for initiation and escalation of oral propranolol rarely changed management and did not predict future adverse events. Few serious adverse events occurred during therapy; none were cardiovascular.