The American Christmas Tree Association indicates that 95 million American households will have Christmas trees in 2017—that represents 76% of all homes. This tradition dates back to Queen Victoria in England. Only 19% of Christmas trees will be harvested live.

Health care providers should be aware that Christmas trees have been associated with allergic contact dermatitis and allergy, and they should be on the lookout for these problems if patients report with rash or other allergic manifestations. This issue is covered in a case report and review in the December issue of journal Contact Dermatitis.

The authors, researchers from the Department of Dermatology and Allergy at the University of Copenhagen in Denmark, attribute most allergic problems to colphonium. Colophonium (also called colophony) is a sticky substance in evergreen trees from the family Pinaceae, which includes pine and spruce.