What's an allergen?

Scientists call substances an allergen when the substance can cause an allergic reaction.   What causes a harmless substance to turn into an allergen?   Good question. The American Academy of Allergy, Asthma and Immunology says this:  “It is not yet fully understood why some substances trigger allergies and others do not, nor why some people have allergic reactions while others do not.  A family history of allergies is the single most important factor that puts you at risk of developing allergic disease.”  The person suffering from an allergic reaction goes through life minding his business.  One day for some reason his body reacts with itching and hives.  Finding out what the person has become allergic to can be difficult and frustrating.  If he visits an allergy doctor, a good examination and talking with the doctor may begin to unravel the mystery.  But sometimes it’s difficult to identify what’s causing the allergic reaction.  Often allergy skin testing can help identify the allergen.  More information from the American Academy of Allergy, Asthma and Immunology can be found at http://www.aaaai.org/conditions-and-treatments/library/at-a-glance/allergic-reactions.aspx