Safety and Tolerability of Accelerated Venom Immunotherapy with Depot Extracts in Insect-Venom-Allergic Patients

Background and Objectives: Hymenoptera venom allergy (HVA) represents one of the most frequent causes of anaphylaxis in adults. Venom immunotherapy (VIT) remains the only causal intervention that effectively reduces the risk of systemic reactions following subsequent stings. Accelerated-induction protocols enable rapid attainment of the maintenance dose; however, data on their safety with depot preparations are still limited. To evaluate the safety of accelerated-induction VIT using a depot preparation in a real-world clinical setting. Materials and Methods: A retrospective, single-center study was conducted between 2022 and 2024; accelerated-induction VIT with a depot preparation was initiated in 54 consecutive patients at a tertiary referral center. All patients had a documented history of systemic allergic reactions after Hymenoptera stings. A three-day accelerated-induction protocol was applied. Safety outcomes and adverse events occurring during the induction phase were systematically recorded and analyzed. Results: All 54 patients successfully achieved the maintenance dose. Adverse reactions were observed only in five patients (9.3%) and were restricted to mild local reactions at the injection site, including erythema and localized swelling. No systemic reactions or cases of anaphylaxis were reported. None of the patients required permanent discontinuation of VIT. Conclusions: Accelerated-induction VIT using a depot preparation demonstrated a favorable safety profile. When performed in an experienced tertiary care setting, this approach allows for rapid attainment of the maintenance dose while maintaining excellent tolerability.