Food allergy is marked by symptoms which mostly occur soon after exposure to food (other types of food allergy, less frequent, occur few hours after consuming certain foods). Since babies are already, during pregnancy or through breast milk, in contact with certain food proteins, an allergic reaction usually occurs after first contact with a food. This may manifest as hives (urticaria), facial swelling (angioedema), vomiting, abdominal pain, diarrhea, shortness of breath or cardiovascular symptoms. The most frequent food allergens in childhood are cow’s milk, hen’s egg, peanut, tree nuts, wheat, soy and fish. Some of those food allergies will outgrow (typically cow’s milk and egg allergy), others can last a lifetime. To test whether the child spontaneously developed a tolerance to the culprit food, it is recommended to perform a regular blood test (measurement of specific IgE) or skin prick test. However, to exclude a food allergy, an oral food challenge should be performed. If there is no spontaneous development of tolerance, an oral immunotherapy  might be tried.