Editing Itch (section)

{{Short description|Uncomfortable skin sensation}}
{{Other uses}}
{{Infobox medical condition
| name          = Itch
| synonyms      = 
| image         = Itch 01.JPG
| caption       = A man scratching his back
| pronounce     = 
| field         = [[Dermatology]]
| symptoms      = [[Scratch reflex|Compulsion to scratch]] an irritated area of skin
| complications = 
| onset         = 
| duration      = 
| types         = 
| causes        = Certain infections, allergies, blood derangements and environmental factors
| risks         = [[Dry skin]]
| diagnosis     = Often based on the causes of itching
| differential  = [[Pain]]
| prevention    = 
| treatment     = [[Antipruritic]]s, [[phototherapy]]
| medication    = 
| prognosis     = 
| frequency     = 
| deaths        = 
}}

An '''itch''' (also known as '''pruritus''') is a [[Wikt:sensation|sensation]] that causes a strong desire or [[reflex to scratch]].<ref name=andersen>{{cite journal |vauthors=Andersen HH, Elberling J, Arendt-Nielsen L |title=Human surrogate models of histaminergic and non-histaminergic itch |journal=Acta Dermato-Venereologica |volume=95 |issue=7 |pages=771–777 |date=September 2015 |pmid=26015312 |doi=10.2340/00015555-2146 |doi-access=free}}</ref> Itches have resisted many attempts to be classified as any one type of [[sense|sensory]] experience. Itches have many similarities to [[pain]], and while both are unpleasant sensory experiences, their behavioral response patterns are different. Pain creates a [[withdrawal reflex]], whereas itches leads to a [[scratch reflex]].<ref name=ikoma>{{cite journal |vauthors=Ikoma A, Steinhoff M, Ständer S, Yosipovitch G, Schmelz M |display-authors=3 |title=The neurobiology of itch |journal=Nature Reviews. Neuroscience |volume=7 |issue=7 |pages=535–547 |date=July 2006 |pmid=16791143 |doi=10.1038/nrn1950 |s2cid=9373105}}</ref>

Unmyelinated [[nerve fibers]] for itches and pain both originate in the [[skin]]. Information for them is conveyed centrally in two distinct systems that both use the same [[nerve]] bundle and [[spinothalamic tract]].<ref>{{cite journal |vauthors=Greaves MW, Khalifa N |title=Itch: more than skin deep |journal=International Archives of Allergy and Immunology |volume=135 |issue=2 |pages=166–172 |date=October 2004 |pmid=15375326 |doi=10.1159/000080898 |s2cid=13376216}}</ref>