Symptoms of a food allergy. The symptoms of a food allergy almost always develop a few seconds or minutes after eating the food. Some people may develop a severe allergic reaction (anaphylaxis), which can be life threatening. The most common type of allergic reaction to food is known as an IgE-mediated food allergy. Symptoms include: 1  tingling or itching in the mouth.  a raised, itchy red rash (urticarial) – in some cases, the skin can turn red and itchy, but without a raised rash.