A review.Perform a partly randomized, parallel-group, controlled (open-label), multicenter trial to compare the safety and tolerability profile of a 7-injection up-dosing schedule with the registered and widely used AIT product Alutard SQ (ALK, based on either 6 grasses and rye, birch, or HDM allergens) with that of the established 11-injection up-dosing schedule for grass pollen allergens.Patients treated with grass allergen extracts were randomized 1:1 to up-dosing with 11 weekly injections (grass-11) or 7 weekly injections (grass-7).In total, 302 (89%) patients experienced 2755 adverse events (AEs), and 269 (79%) experienced 2162 TRAEs.Four systemic allergic reactions were identified in the grass-11 group (all serious) and 3 in the grass-7 group (1 serious and 2 nonserious), subheading Systemic allergic reaction.Our results suggest that the 7-injection up-dosing schedules for grass, tree, and HDM have an acceptable safety and tolerability profile, which is generally comparable to the 11-injection up-dosing schedule for grass in adolescents and adults (12-65 years) with moderate to severe ARC induced by the resp. allergen.SCIT with Alutard SQ based on the 7-injection up-dosing schedules may improve the convenience of treatment and, thus, facilitate patients' access to the benefits of AIT.