At some point in their lives, allergy symptoms will affect between ten and fifteen percent of the population. The symptoms are varied and can include canker sores, chronic bladder or ear infection, hyperactivity, insomnia, irritability, joint pain, Asthma, headache, itchy nose and hypoglycemia. One way to diagnose allergens is the pinprick test. In this test, food extracts are scratched into the patient's skin. If the patient is allergic, a welt will form. Blood tests are also used to diagnose food Allergies. The best way to avoid allergy symptoms is to avoid those foods that cause them.