View source for Erythema

{{Short description|Redness of the skin or mucous membranes}}
{{Distinguish|arrhythmia|erythremia}}
{{More citations needed|date=December 2009}}
{{Infobox medical condition
| name            = Erythema
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| image           = Erythema migrans - erythematous rash in Lyme disease - PHIL 9875.jpg
| caption         = [[Pathognomonic|Characteristic]] "bull's eye" rash ([[erythema chronicum migrans|erythema migrans]]) of early [[Lyme disease]]
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| field           = [[Dermatology]]
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'''Erythema''' ({{langx|grc|ἐρύθημα}}, {{ety|el|erythros|red}}) is redness of the skin or [[mucous membrane]]s, caused by [[hyperemia]] (increased blood flow) in superficial [[capillaries]].<ref>{{cite book |title=Mosby's Medical Dictionary |edition=9th |year=2013 |publisher=Elsevier |location=St. Louis, Missouri |isbn=978-0-323-08541-0}}</ref> It occurs with any skin injury, infection, or [[inflammation]]. Examples of erythema not associated with pathology include [[blushing|nervous blushes]].<ref>{{Cite encyclopedia |title=Erythema |encyclopedia=[[Mosby's Medical, Nursing & Allied Health Dictionary]] |edition=Fourth |publisher=Mosby-Year Book |year=1994 |page=570}}</ref>

== Types ==
{{Div col|colwidth=17em}}
* [[Erythema ab igne]]
* [[Erythema chronicum migrans]]
* [[Erythema induratum]]
* [[Erythema infectiosum]] (or [[fifth disease]])
* [[Erythema marginatum]]
* [[Erythema migrans]]
* [[Erythema multiforme]] (EM)
* [[Erythema nodosum]]
* [[Erythema toxicum]]
* [[Erythema elevatum diutinum]]
* [[Erythema gyratum repens]]
* [[Keratolytic winter erythema]]
* [[Palmar erythema]]
{{Div col end}}

== Causes ==
It can be caused by [[infection]], [[massage]], electrical treatment, [[acne]] medication, [[allergy|allergies]], [[psoriasis]], [[mast cell activation syndrome|mast cell activation syndrome (MCAS)]],<ref name="PMID35605594">{{cite journal |vauthors=Valent P, Hartmann K, Bonadonna P, Niedoszytko M, Triggiani M, Arock M, Brockow K |title=Mast Cell Activation Syndromes: Collegium Internationale Allergologicum Update 2022 |journal=Int Arch Allergy Immunol |volume=183 |issue=7 |date=2022-05-23 |DOI=10.1159/000524532 |PMC=9393812 |PMID=35605594 |pages=693–705  |url=|doi-access=free}}</ref> exercise, solar radiation ([[sunburn]]), [[photosensitization]],<ref>{{citation | author1=Jane C. Quinn | author2=Yuchi Chen | author3=Belinda Hackney | author4=Muhammad Shoaib Tufail | author5=Leslie A. Weston | author6=Panayiotis Loukopoulos | title = Acute-Onset High-Morbidity Primary Photosensitisation in Sheep Associated with Consumption of the Casbah and Mauro Cultivars of the Pasture Legume Biserrula | journal = BMC Veterinary Research | year = 2018 | volume=14 | issue=1 | page=11 | doi= 10.1186/s12917-017-1318-7| pmid=29325550 | pmc=5765607 | doi-access=free }}</ref> [[acute radiation syndrome]], [[Mercury poisoning|mercury toxicity]], [[blister agent]]s,<ref>[https://fas.org/nuke/guide/usa/doctrine/army/mmcch/Vesicant.htm#CLINICAL Vesicant] {{webarchive|url=https://web.archive.org/web/20171212112435/https://fas.org/nuke/guide/usa/doctrine/army/mmcch/Vesicant.htm | date=2017-12-12 }} EFFECTS</ref> [[Niacin (substance)|niacin]] administration,<ref>{{cite journal |vauthors=Weterle R, Rybakowski J |pmid=2084715 |title=Test niacynowy w schizofrenii |trans-title=The Niacin Test in Schizophrenia |language=Polish |journal=Psychiatr Pol |date=Mar–Apr 1990 |volume=24 |issue=2 |pages=116–20}}</ref> or waxing and tweezing of the hairs—any of which can cause the affected capillaries to dilate, resulting in redness. Erythema is a common side effect of [[radiotherapy]] treatment due to patient exposure to [[ionizing radiation]].

== Diagnosis ==
Erythema disappears on finger pressure ([[Blanch (medical)|blanching]]), whereas [[purpura]] or bleeding in the skin and [[pigmentation]] do not. There is no temperature elevation, unless it is associated with the dilation of arteries in the deeper layer of the skin.{{Citation needed|date=June 2010}}

== See also ==
* [[Hyperemia]]
* [[Flushing (physiology)]]
* [[List of cutaneous conditions]]

== References ==
{{Reflist}}

== External links ==
{{wiktionary}}
{{Commons category|Erythemas}}

{{Medical resources
|   DiseasesDB     = 4466
|   ICD10          = {{ICD10|L|51||l|50}}-{{ICD10|L|54||l|50}}
|   ICD9           = {{ICD9|695}}
|   ICDO           =l
|   OMIM           =
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|   eMedicineSubj  =
|   eMedicineTopic =
|   MeshID         = D004890
}}
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[[Category:Dermatologic terminology]]
[[Category:Radiation health effects]]
[[Category:Symptoms and signs: Skin and subcutaneous tissue]]