An allergy is an immune response to a particle that the body considers foreign or harmful. Allergies are exaggerated hypersensitivity reactions in some people, to certain particles like dust or dander, which may not elicit an allergic response in some other person. Substances that cause these reactions are known as 'allergens'. Allergic reactions are mediated by immunoglobulin E (IgE).
There are different types of allergies, depending upon the different substances ...
