Adverse reactions to immunotherapy are associated with different patterns of sensitization to grass allergens

The aim of the study was to investigate whether adverse drug reactions ( ADR s) during immunotherapy with a grass extract ( AVANZ ® Phleum, ALK ‐Abelló) are related to the different patterns of sensitization of patients to grass allergens. A total of 192 patients with rhinitis and/or asthma sensitized to grass pollen received a 4‐week updosing with five injections. ADR s were evaluated following EAACI guidelines. A total of 432 ADR s in 133 (69%) patients were recorded, 64% local and 31% systemic. There was a significant association between the number of grass allergens that sensitized the patients and the total number of ADR s ( P  = 0.004) occurred locally ( P  = 0.003) and systemically ( P  = 0.01). Sensitization to Phl p1 + Phl p5 or Phl p1 + Phl p5 + Phl p12 was significantly associated with a higher frequency of local or systemic reactions ( P  = 0.001, both). Different patterns of sensitization to grass allergens may potentially be considered a risk marker to the development of ADR s to immunotherapy.