There are many different types of allergy and sinus problems and therefore many different types of doctors who specialize in treating the various symptoms. Allergies are reactions of the body to a certain pathogen or allergen. Essentially they are body's ways of attacking a problem, but the attack sometimes harms the body itself. In other words, an allergy is an immune response that is so severe that it harms the human body. Allergic reactions can vary from small to so severe that they may cause death. For example, some people are so allergic to bee stings that their whole body swells up (swelling is one way for the body to rid itself of a pathogen or allergen) to the point where the heart and brain start to lose function.
