Does the thought of putting up the Christmas tree fill you with dread instead of excitement? Do you have visions of tissues and antihistamine instead of sugarplums dancing in your head? Christmas trees and other decorations can trigger allergies in many people. Tree sap, pollen and terpenes — compounds that give pine trees their scent — can all make allergy sufferers sneeze. …Live trees can be full of mold. A study last year at SUNY Upstate Medical University found 53 kinds of mold in live Christmas trees. Most of those molds are potential allergens and are known to increase the risk of wheezing, persistent coughing and allergic sensitization in infants. …If pollen is a problem, consider buying a Leland cypress tree. According to the National Christmas Tree Association, this hybrid is the most popular Christmas tree in the Southeast, and does not produce pollen or sap.