Pretreatment with antihistamines reduces large local reactions in venom immunotherapy

Premedication with oral antihistamines during venom immunotherapy (VIT) significantly reduces the frequency of large local reactions (LLR), but it does not have a significant effect on systemic adverse events (AE), according to a study.

Additionally, the type of venom preparation used (aqueous or depot) does not significantly impact the frequency of systemic AE or the overall effectiveness of VIT, but LLR are less frequently observed when depot preparations are used.

The study, conducted as an open, prospective, observational trial, involved 1,425 patients, with 1,342 receiving VIT.

During the up-dosing phase, 52.1% of patients took oral antihistamines as premedication, while during the maintenance phase, this figure dropped to 19.7%. The study found that taking antihistamines had no significant impact on the frequency of systemic AE. However, it did result in a reduction of large local reactions (LLR).

The choice of venom preparation was also examined, with aqueous preparations being favored for up-dosing (73.0%) and depot preparations for the maintenance phase (64.5%). The type of venom preparation used did not demonstrate a notable influence on the frequency of systemic AE or the overall effectiveness of VIT. However, LLR were less frequently observed when depot preparations were used.

Reference
Arzt-Gradwohl L, Annik Herzog S, Aberer W, et al. Influencing factors on the safety and effectiveness of venom immunotherapy. J Investig Allergol Clin Immunol. 2023;doi: 10.18176/jiaci.0967. Epub ahead of print. PMID: 37937715.