Objective: We conducted a large observational study in 193 children and adolescents with allergic rhinitis due to grass or tree pollens to evaluate the safety and tolerability of an ultrarush high-dose sublingual immunotherapy (SLIT) regimen reaching a maintenance dose of 300 index of reactivity within 90 minutes.

Methods: Children and adolescents aged 5 to 17 years with at least a 1-year medical history of allergic rhinitis with or without mild to moderate asthma due to tree pollens (birch, alder, hazel) or grass pollens (cocksfoot, meadow grass, rye grass, sweet vernal grass, timothy) were recruited. Standardized grass and tree pollen allergen extracts were used for ultrarush titration and subsequent coseasonal maintenance.

Results: During ultrarush titration, 60 patients (31%) reported 117 predominantly mild and local adverse events, which resolved within 150 minutes. During the maintenance phase, 562 adverse events were reported; the most frequent local events were oral pruritus, burning sensation, lip or tongue swelling, and gastrointestinal symptoms, and the most frequent systemic events were rhinoconjunctivitis and asthma. There was 1 clinically significant asthma event in an 11-year old boy with known asthma in whom SLIT was resumed after an interval of 4 days.

Conclusion: Ultrarush titration was safe and well tolerated. Pediatric patients with asthma should be carefully monitored and adequately trained to use their rescue medications.

Key words: Grasses. Trees. Ultrarush. Sublingual immunotherapy. Children. Safety. Allergic rhinitis. Asthma.