By: Allergies in various forms affect about one out of four people. To some, they are merely a nuisance, but to others they are a very distracting and potentially serious chronic condition. Allergies are the result of the body’s immune system recognizing otherwise harmless substances as threats, and then mounting an attack against those substances, which ends up harming the person themselves. In this article, the term for any substance that causes an allergic reaction will be an allergen. By: Most people with asthma or hay fever or other outdoor allergies think of their home as a haven where they can escape their allergies.