Early-onset respiratory adverse event patterns of omalizumab in pediatric patients: an age-stratified FAERS pharmacovigilance study

OBJECTIVES: To compare age-specific respiratory adverse event (AE) reporting patterns associated with omalizumab in pediatric and adult patients using FAERS, interpreting findings as signal-detection rather than causal or incidence evidence. METHODS: FAERS reports for omalizumab/Xolair from Q1 2004 to Q4 2025 were analyzed after FDA-recommended deduplication. Reports were stratified as pediatric (<18 years) or adult (≥18 years); reports with missing age were described but excluded from age-stratified comparisons. Signal detection used ROR, PRR, BCPNN/IC, and MGPS/EBGM. PTs with ≥3 reports were evaluated, with emphasis on signals concordant across algorithms. Early onset was predefined as valid time-to-onset (TTO) ≤100 days. RESULTS: Among 62,925 omalizumab-associated AE reports, 2,792 were pediatric, 28,075 adult, and 32,058 (50.94%) lacked age information. Respiratory, thoracic and mediastinal disorders and immune system disorders were prominent in both age-known groups. Pediatric reports showed concentrated respiratory PTs, including asthma, dyspnoea, cough, wheezing, and asthmatic crisis. Asthmatic crisis showed strong pediatric disproportionality, although this may reflect underlying asthma severity, exacerbation, treatment failure, differential reporting, and potential drug-related events. Valid TTO records indicated earlier reported onset in pediatric patients than adults (median: 34.4 vs. 63.1 days), with clustering within the first 100 days. CONCLUSION: FAERS reports suggest age-related differences in omalizumab-associated respiratory AE reporting and TTO patterns. These hypothesis-generating signals do not establish causality, incidence, or risk magnitude but support closer early respiratory monitoring in pediatric patients, with careful consideration of indication-related confounding.