Abstract
Background: There are three broad types of food allergies, including IgE-mediated reactions, non-IgE-mediated reactions, and mixed reactions. The onset of IgE-mediated food allergies is usually rapid and can sometimes lead to serious illness. Non-IgE-mediated and mixed types of food allergies can cause significant morbidity as a result of chronic disease. Objectives: This study aimed to compare various types of food allergies and discuss the basis of their different presentations. Methods: This study was conducted on children aged 2 - 12 years old with signs or symptoms of food allergy in the allergy clinics of Azad University Hospitals, Tehran, Iran, from January 2019 to January 2020. Food allergy was evaluated in these patients by careful history, physical exam, skin prick test, and atopy patch test. Results: A positive family history of atopy was detected in the first-degree relatives of 82 (63%) patients. All the children were exclusively breastfed at the beginning. A total of 61 patients had positive skin prick test (SPT), and 68 patients had positive atopy patch test (APT) results. Among food allergens, a significant correlation was detected between positive atopic patch test results and hypersensitivity reactions to cow’s milk (P value = 0.001), beef (0.002), and tomato (0.04). There was the same significant correlation between positive skin prick test results, allergens, and wheat (P value = 0.01). Conclusions: Although skin prick and atopy patch tests may help identify the culprit foods, oral food challenges are the mainstay of the diagnosis.