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Characteristic "bull's eye" rash (erythema migrans) of early Lyme disease

Erythema (from Greek erythros 'red') is redness of skin that is generally not transient.[1] It occurs with any skin injury, infection, or inflammation. Examples of erythema not associated with pathology include nervous blushes.[2]

It is caused by hyperemia (increased blood flow) in superficial capillaries.[1]



It can be caused by infection, massage, electrical treatment, acne medication, allergies, exercise, solar radiation (sunburn), photosensitization,[3] acute radiation syndrome, mercury toxicity, blister agents,[4] niacin administration,[5] or waxing and tweezing of the hairs—any of which can cause the capillaries to dilate, resulting in redness. Erythema is a common side effect of radiotherapy treatment due to patient exposure to ionizing radiation.


Erythema disappears on finger pressure (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]

See also


  1. 1.0 1.1 Hopcroft, Keith; Forte, Vincent (2020). "Erythema". Symptom Sorter. Boca Raton: CRC Press. pp. 402–404. ISBN 978-0-367-46810-1. Archived from the original on 2023-10-20. Retrieved 2023-09-19.
  2. erythema, Mosby's Medical, Nursing & Allied Health Dictionary, Fourth Edition, Mosby-Year Book 1994, p. 570.
  3. Jane C. Quinn; Yuchi Chen; Belinda Hackney; Muhammad Shoaib Tufail; Leslie A. Weston; Panayiotis Loukopoulos (2018), "Acute-onset high-morbidity primary photosensitisation in sheep associated with consumption of the Casbah and Mauro cultivars of the pasture legume biserrula", BMC Veterinary Research, 14 (1): 11, doi:10.1186/s12917-017-1318-7, PMC 5765607, PMID 29325550
  4. Archived 2017-12-12 at the Wayback Machine EFFECTS
  5. Weterle R, Rybakowski J (Mar–Apr 1990). "Test niacynowy w schizofrenii" [The niacin test in schizophrenia]. Psychiatr Pol. 24 (2): 116–20. PMID 2084715.

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