What is Itch?
'''Itch''' ([[Latin]]: '''pruritus''') is an unpleasant [[sensation]] that leads to the desire or [[reflex]] to [[wikt:scratch|scratch]]. Itch has many similarities to [[pain]] and both are unpleasant sensory experiences but their behavioral response patterns are different. Pain creates a reflex withdrawal while itch leads to a scratch reflex.<ref>Ikoma, A., Steinhoff, M., Stander, S., Yosipovitch, G., Schmelz, M. (2006). The neurobiology of itch. Nature Reviews Neuroscience, 7(7), 535-547.</ref> [[Nerve]] [[fiber]]s for itch and pain both are in the [[skin]], but information for them is sent centrally in two distinct systems that both use the same [[nerve]] bundle.<ref>Greaves, M.W., Khalifa, N. (2004). Itch: More than skin deep. Int Arch Allergy Immunol, 135, 166-172.</ref> Historically, the sensations of itch and pain have not been considered to be independent of each other until recently where it was found that itch has several features in common with pain but has important differences.<ref>Twycross, R., Greaves, M.W., Handwerker, H., Jones, E.A., Libretto, S.E., Szepietowski, J.C., Zylicz, Z. (2003). Itch: scratching more than the surface. Q J Med, 96, 7-26.</ref> [[Image:Squirrel Scratching the Armpit with its Hindlimb.jpg|thumb|right|250px|Chipmunk scratching itself in a response to an itch]] ==Causes== [[Image:Scabies-burrow.jpg|right|thumb|[[Scabies]] is one cause of itching. ]] The feeling of itchiness can be caused by a movement of hair or the release of a chemical ([[histamine]]) from cells under the skin. Itchiness is regarded as protective, as it helps creatures remove [[parasites]] that land on their skin. Itching can be caused by: *[[Food poisoning]] *[[Xerosis]]. This is the most common cause, frequently seen in winters. Associated with older age, frequent bathing in hot showers or baths, and high temperature and low humidity environments. * [[Dermatology|Skin conditions]] (such as [[psoriasis]], [[eczema]], [[sunburn]], [[athlete's foot]], [[hidradenitis suppurativa]] and many others). Most