Food allergies potentially causing itchy skin include allergies to wheat, eggs, tree nuts, peanuts, fish, shellfish, wheat and soy, as noted by WebMD. In children and adults, skin reactions to food allergens range from uncomfortable rashes to hives; upon consuming a triggering food, most people display symptoms within several minutes to 2 hours after eating. In addition to skin reactions, some people develop other reactions, ranging from abdominal discomfort and cramps to life-threatening anaphylaxis reactions.
According to WebMD, children and adults experience the same skin reactions to triggering foods, although common triggering foods differ among those age groups. Children typically develop allergies to eight foods: wheat, soy, tree nuts, specifically walnuts, pecans and almonds, along with peanuts and eggs. Adults usually develop allergies to fish, shellfish, tree nuts and peanuts. In the range of food allergy reactions, experts consider skin reactions relatively mild. In addition to itchy skin, allergy reactions include a tingling sensation in the mouth, swelling of the throat and tongue, vomiting and diarrhea. The most serious symptoms include difficulty breathing, a drop in blood pressure and unconsciousness; these symptoms indicate life-threatening anaphylaxis shock. Upon experiencing reactions after consuming triggering foods, people visit their physicians or allergy doctors for testing. Tests for allergies include a skin scratch test and a blood test.