D3.199 - Severe systemic allergic reaction following violation of elimination diet in a patient with sensitization despite achieved remission on allergen-specific immunotherapy

Allergen-specific immunotherapy (ASIT) is a highly effective causal treatment for IgE-mediated allergic diseases such as allergic rhinoconjunctivitis. It enables significant reduction in symptom severity and achievement of sustained clinical remission with complete or near-complete absence of symptoms for a prolonged period. However, there remains a risk of severe systemic allergic reactions upon contact with cross-reactive allergens via food products. This clinical case demonstrates the critical need for ongoing adherence to elimination measures to prevent such complications.

CASE REPORT. Female, 48 years old, has suffered from seasonal allergic rhinoconjunctivitis since childhood with peak symptoms in August–September, including frequent sneezing, rhinorrhea, lacrimation, and intense itching in the eyes and nose. ALEX2 testing showed total IgE 109 kU/L, sIgE to ambrosia (Amb a 1) 3.57 kU/L and  Alternaria alternata (Alt a 1) 11.84 kU/L. She underwent a course of ASIT with polymerized A. alternata allergoid, resulting in sustained remission with complete absence of clinical manifestations.

Despite dietary recommendations, the patient consumed blue cheese and nuts. This led to generalized urticarial rash, Quincke’s edema of the face and lips, severe general weakness, nasal congestion, chills, lumbar pain, and diarrhea. The patient sought medical help 20 minutes later. The condition was assessed as severe; emergency treatment was provided, followed by a hospitalization and discharge with clinical improvement.

DISCUSSION. The acute reaction likely occurred due to direct contact with potentially cross-reactive food components, despite successful ASIT and achieved remission. Immunotherapy effectively controls the main disease manifestations associated with exposure but does not always fully prevent systemic IgE-mediated reactions upon oral or massive exposure to cross-reactive proteins. This underscores that elimination of potential triggers is a key and mandatory component of comprehensive allergy management, even in the absence of active symptoms.

CONCLUSIONS. Patients with sensitization must strictly adhere to an elimination diet and avoid potential triggers even after achieving sustained remission and complete absence of symptoms as violation can lead to potentially life-threatening systemic allergic reactions. ASIT is a highly effective causal treatment method, but maximum efficacy and success are possible only when combined with ongoing elimination measures and comprehensive patient risk-related education.