Follow-up after systemic adverse reactions of immunotherapy

Out of 280 immunotherapy (IT)-treated patients in our allergy clinic, 37 (13%) developed systemic adverse reactions. Parietaria judaica (Pj) extract, a highly allergenic pollen in northern Israel, was part of the IT regimen in 46% of treated patients who developed systemic adverse reactions. Twenty-six (70%) of systemic adverse reactions occurred during the buildup phase, whereas 11 (30%) occurred in the maintenance phase of treatment. Mild systemic reactions developed in 15/37 (40%), moderate in 20/37 (54%), and severe in 2/37 (5%) of patients. In 22/37 (59% of our IT-treated patients, adverse reactions developed within 30 min after injection. Among these were the two patients with severe systemic reactions. In 19%, moderate adverse reactions appeared at 30-60 min; in 22%, mild to moderate reactions appeared after 1-2 h. Our study concludes that severe systemic reactions to IT usually appear within 30 min after injection. In Israel, IT with highly allergenic pollens such as Pj frequently causes systemic reactions, even during the maintenance phase of treatment. In such cases, the reduction of IT dosage should be more than 50% during the pollen season, and a waiting period of 1 h should also be considered.