Optimizing Allergen Immunotherapy Safety: What Do We Know and What Are the Unmet Needs

Subcutaneous immunotherapy (SCIT) is generally safe yet there remains a small risk of fatal and near-fatal injections. Factors that should be considered in the initial risk assessment for systemic reactions to SCIT include poorly controlled asthma, high degree of allergen sensitivity, history of prior systemic reactions, comorbid illness, and building up injections during the height of pollen season. Future studies should evaluate the aforementioned risk factors and also assess protocol modifications including antihistamine pretreatment, lower or higher starting doses (silver [1:10,000 v/v] vs red [1:1000 v/v]) and different buildup regimens with different dose increases (0.05 vs 0.1 mL). Finally, risk management after systemic reactions (SR) needs to be further investigated, including when to discontinue SCIT, how far to decrease the dose after SR, optimal pretreatment regimens, when to increase wait times, and when to prescribe epinephrine autoinjectors. Sublingual immunotherapy (SLIT) is generally felt to be safer, though anaphylaxis has been reported. Local side effects (oral and gastrointestinal) represent the majority of all reported SLIT adverse reactions and affect up to 75 % of patients. There are a multitude of unanswered questions related to SLIT safety, including the safety of using multiple allergens, using SCIT + SLIT simultaneously, dosage adjustments for missed doses, how long to hold a dose (after infections, dental work, asthma), and identifying SR risk factors.