Editing Itch (section)

=== Environmental and allergic ===
*[[Allergic reaction]] to contact with specific chemicals, such as [[urushiol]], derived from [[poison ivy]] or [[poison oak]], or [[Balsam of Peru]], found in many foods and fragrances.<ref>{{cite journal |vauthors=Pfützner W, Thomas P, Niedermeier A, Pfeiffer C, Sander C, Przybilla B |display-authors=3 |title=Systemic contact dermatitis elicited by oral intake of Balsam of Peru |journal=Acta Dermato-Venereologica |volume=83 |issue=4 |pages=294–295 |date=2003-02-20 |pmid=12926805 |doi=10.1080/00015550310016599 |doi-access=free}}</ref><ref>{{cite journal |vauthors=Usatine RP, Riojas M |title=Diagnosis and management of contact dermatitis |journal=American Family Physician |volume=82 |issue=3 |pages=249–255 |date=August 2010 |pmid=20672788 |url=http://www.aafp.org/afp/2010/0801/p249.html |access-date=2014-04-09 |publisher=Aafp.org |archive-date=2014-04-09 |archive-url=https://web.archive.org/web/20140409161328/http://www.aafp.org/afp/2010/0801/p249.html |url-status=live }}</ref> Certain allergens may be diagnosed in a [[patch test]].<ref>{{cite book |url=https://books.google.com/books?id=QhWgKgiT6FoC&pg=PA329 |title=Metalworking Fluids |edition=Second |publisher=CRC Press |isbn=142001773X |date=2006 |vauthors=Byers JP |access-date=2016-03-05 |archive-date=2023-01-12 |archive-url=https://web.archive.org/web/20230112213927/https://books.google.com/books?id=QhWgKgiT6FoC&pg=PA329 |url-status=live }}</ref><ref>{{cite book |url=https://books.google.com/books?id=Me5rAAAAMAAJ&q=pruritus+%22patch+test%22 |title=Introduction to clinical allergy |vauthors=Feingold BF |veditors=Byers JP |publisher=the University of Michigan |date=1973 |isbn=0398027978 |access-date=2020-06-24 |archive-date=2023-01-12 |archive-url=https://web.archive.org/web/20230112223856/https://books.google.com/books?id=Me5rAAAAMAAJ&q=pruritus+%22patch+test%22 |url-status=live }}</ref>
*[[Foreign body|Foreign object]]s on the skin are the most common cause of non-pathological itching. 
*[[Photodermatitis]]&nbsp;– [[sunlight]] reacts with chemicals in the skin, leading to the formation of irritant metabolites.
*[[Urticaria]] (also called [[hives]]) usually causes itching.