Most people use the word “allergy” to describe all types of hypersensitivity. In this chapter, the most common forms of true allergy are described. A specific antibody — called IgE — is associated with these conditions. The IgE antibody is found in high levels in allergic people. It reacts with symptom-causing allergens such as pollen, mold spores, animal dander, dust mites, and certain types of food or medications.