Risk management in allergen immunotherapy

The major risk of allergen immunotherapy is the development of systemic anaphylactic reactions. The reported frequency of systemic reactions after allergen immunotherapy varies from < 1% in patients receiving conventional immunotherapy to > 36% in patients receiving rush immunotherapy. Fatal and systemic reactions to allergen immunotherapy have similar characteristics. The onset of both types of reaction occurs < 30 minutes after injection in approximately 70% of patients. The most common risk factors for fatal and systemic reactions to allergen immunotherapy include a history of asthma, increasing allergen dose, high allergen sensitivity, previous systemic reaction, and injection during an active allergen season. On the basis of findings from several studies, precautions during allergen immunotherapy have been recommended. In addition, several interventions, including premedication with antihistamines or corticosteroids, measurement of peak flow before injection, and access to an antihistamine or injectable epinephrine after an allergen injection, have been suggested as measures to prevent reactions to and improve the safety of allergen immunotherapy. However, additional studies are necessary before these regimens are implemented routinely in allergen immunotherapy protocols.