Allergic reactions are hypersensitive to patient contact with certain chemicals or particles answers. The substance that causes this reaction is called an allergen. When the patient contact with the allergic substance occurs, the first thing that happens is that the immune system responds by automatically releasing large numbers of antibodies called IgE (immunoglobulin E). But after a long period of exposure to the allergen, the allergic reaction is materialized. The causes of allergies are varied (seller's genetic tendency to allergies), and types (foods, pollen, animals, dust mites, insect bites, etc.). Treatment depends on the type of allergy, but the most common solution is vaccination. To diagnose allergic reactions it is customary to use allergy testing, blood tests or other tests follow.