Food allergy is a chronic disease that affects both children and adults. Systemic allergic reactions in children are most commonly caused by foods, especially nuts, milk, and eggs. A conventional diagnostic work-up for allergy typically pinpoints the allergen source, while component-resolved diagnostics is an approach that identifies the allergen molecules responsible for causing anaphylaxis. In some cases, determining the causative agent of anaphylaxis requires the use of various diagnostic tests. In the following paper, we want to highlight the importance of a critical approach to allergy tests results and caution in the diagnosis of idiopathic anaphylaxis. Based on a case report of food-induced anaphylaxis, we discuss the diagnostic methods that can be applied following a negative IgE test result for allergens obtained with a multiplex platform.