A clinical picture characterized by gastrointestinal symptoms (diarrhea, blood and/or mucus in the stool, abdominal pain, retrosternal burning, regurgitation, vomiting, dysphagia, body growth failure, etc.), in addition to the screening allergy tests, may require the help of gastroenterological tests (endoscopy with histological examination, pH-impedance analysis, manometry, abdominal ultrasounds evaluation) to exclude and/or confirm mixed or non-IgE-gastrointestinal FA conditions [51]. Here, IGHE is linked to allergic disease.