Allergy is the result of a complex immune system that identifies foreign substances and produces antibodies to eliminate them. When there is an over-reaction to certain foreign substances, the IgE antibodies produced by the body will remain in the body, and when exposed to the same type of substance that causes allergy, a complex series of reactions will occur, secreting histamine and other chemical mediators, causing the symptoms of an allergic reaction. If you have the following allergy symptoms in your life and work: sneezing, wheezing, nasal congestion and coughing, suggesting rhinitis, asthma, possibly drug allergy or respiratory allergy; itchy eyes, mouth and throat are manifestations of respiratory allergy; stomach pain, frequent indigestion and heartburn may be manifestations of food allergy; skin irritation, itching, redness or swelling may be related to contact, drugs, food and insect bites. Allergies may be related to contacts, medications, food and insect bites; joint stiffness, pain and swelling suggest food or drug allergies.