This is kind of control mechanism that helps in identifying the foods, which are okay, and the foods that may cause a problem. Be on the lookout for allergic responses. The most common allergic skin reaction to a food is a red itchy eruption on the skin that arises suddenly and disappears as 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, diarrohea 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 diarrhoea may be caused by excess sugar in fruit juice, also a non-allergic response.