Yes, it is possible for someone to be allergic to a Christmas tree. Many people can have an allergic reaction to the pollen or sap from Christmas trees, which can cause symptoms such as sneezing, runny nose, itchy eyes, or even asthma attacks. The level of allergic reaction can vary from person to person, and some people may not experience any symptoms at all. If you suspect you may be allergic to Christmas trees, it's best to consult with a doctor or allergist to determine the cause and best course of treatment.