Two factors come into play with all allergic reactions. These are the allergen and the person who is sensitive to it. An allergen is any substance that causes an allergic reaction in an individual. To understand some of the common causes of allergic reactions, a little simple science is all that is needed.

There is little good news associated with finding out that you are allergic. Unfortunately, all too many folks have first hand experience of allergies and allergic reactions. The itchy eyes, runny nose, skin rash and other assorted symptoms are uncomfortably recognizable. However a more exact medical definition of the causes of allergies may well be helpful, since it is the first step towards diagnosis along with treatment for the correct condition.