This is the control' mechanism that helps identify which foods are okay, and which foods may be a problem. Be on the lookout for allergic responses. The most common allergic skin reaction to a food is red, itchy hives that arise suddenly and disappear quickly. Another skin reaction is a chronic itchy inflammation of the skin known as atopic dermatitis. Itchy, congested nose is a common respiratory tract allergic response.
Eyes can react by becoming red, swollen and itchy.
Persistant, chronic ear infections may be an indicator of a food allergy. That's because an allergy can cause congestion in the eustachian tubes, connecting the ears to the nose. However, the most common symptoms overall are vomiting, diarrhea and abdominal cramping. Unfortunately these symptoms are common indicators of food intolerances, especially lactose intolerance. Some of the natural acids in fruits may cause a rash around the mouth, but is not an allergy, and diarrhea may be caused by excess sugar in fruit juice, also a non-allergic response.