Fatty resin that when applied topically can cause allergic skin reactions and contact dermatitis. It also has the potential to cause photodermatitis and phototoxicity. Balsam peru is also a standard used in patch tests for skin sensitivity due to its high incidence of causing reactions (Sources: www.naturaldatabase.com; and Journal of the American Academy of Dermatology, December 2001, pages 836–839). Among 3,000 known allergens, balsam peru is ranked in the top ten for most frequent offenders (Source: Deutsche Medizinische Wochenschrift, July 2006, pages 1584–1589).