IGHE and urticaria: Onyimba et al. [5] categorized food-related symptoms by affected systems—gastrointestinal (e.g., abdominal pain, diarrhea), skin (e.g., urticaria, pruritus), respiratory (e.g., wheezing, nasal congestion), and systemic (e.g., hypotension, fatigue)—but only about half of such adverse reactions are attributable to IgE-mediated mechanisms.