Christmas trees can cause allergies in some people, especially those who are sensitive to the pollen or other particles that the tree can release into the air. Some of the common symptoms of a Christmas tree allergy include sneezing, runny nose, itchy eyes, and skin rashes. If you think you may have an allergy to Christmas trees, it's best to avoid being around them for extended periods of time or take precautions such as wearing a mask or using an air purifier when you are around them.