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Erythema toxicum neonatorum

Medical Professionals

Professional Reference articles are designed for health professionals to use. They are written by UK doctors and based on research evidence, UK and European Guidelines. You may find the Erythema toxicum neonatorum article more useful, or one of our other health articles.

Synonyms: erythema neonatorum allergicum; toxic erythema of the newborn

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What is erythema toxicum neonatorum?1

Erythema toxicum neonatorum (ETN) only occurs in the newborn, usually presenting within the first week of life. It has the appearance of small, erythematous papules and vesicles. Occasionally pustules also occur. The lesions are often surrounded by areas of diffuse blotchy erythema, giving the appearance of a distinct halo.

Individual lesions are quite transient and usually disappear quickly, only to be replaced by others in different parts of the body. The condition is benign, causes no symptoms and resolves spontaneously, usually within 7-14 days.


The condition has been known throughout the ages and was described by ancient Mesopotamian physicians.2 The exact cause is not known but some authorities have attributed it to an allergy because of the prominence of eosinophils within the lesions. Some popular theories include:

  • An immune system reaction involving hair follicles (the condition normally occurs on hair-bearing areas and clusters of mast cells can be seen around hair follicles).3

  • An innate immune response against commensal colonisation by organisms such as Group B streptococcus.4 .

  • Over-expression of high mobility group box chromosomal protein 1 (HMGP-1), a proinflammatory cytokine released by macrophages and keratinocytes4

  • A transient adjustment reaction of the newborn skin to mechanical or thermal stimulation.2

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How common is erythema toxicum neonatorum? (Epidemiology)

A Spanish study reported a prevalence of 16.7%,5 a Turkish study reported a prevalence of 13%6 and an Indian study 23%.7 There is considerable geographical variation. A Chinese study estimated prevalence to be about 44%.8

Risk factors

Studies have identified the following risk factors:5 8

  • Caucasian race.

  • Higher birth weight.

  • Greater gestational age.

  • Maternal age less than 30 years.

  • Term birth.

  • The birth season (higher in summer and autumn).

  • Feeding with milk powder substitute or a mixed diet.

  • The length of labour in vaginal delivery.

Some studies suggest it is more common in male infants and in babies born to women who have had two or fewer pregnancies; however, other studies have contradicted these findings.

Erythema toxicum neonatorum symptoms (presentation)8

The typical rash appears in newborns between the ages of 3 days to 2 weeks. Rarely, it can occur within the first 48 hours. The transience of the lesions is characteristic; they can appear or disappear within minutes to hours.

The lesions most commonly start on the trunk and involve the buttocks and proximal parts of the limbs.5 The face can also become involved.1

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Differential diagnosis1 8


  • The characteristic appearance of the lesions, their fleeting nature and the lack of systemic features make the condition fairly easy to diagnose clinically.

  • If the clinical picture is atypical, material taken from a pustule should be examined to exclude bacterial, viral and fungal infections.

  • A peripheral blood film may show eosinophilia.

  • If systemic sepsis is suspected, blood cultures should be taken to exclude Group B streptococcus, Listeria spp., Escherichia coli and other pathogens.

  • If necessary, a skin biopsy should be taken. Typically, there is accumulation of primary eosinophils. Other features may be neutrophils in the follicular epithelium, hyperkeratosis and follicular plugging.

Erythema toxicum neonatorum treatment2

The condition is self-limiting and requires no treatment. Parents should be reassured about this but advised to report any atypical features.


No complications occur. Despite the presence of eosinophils within the lesions, no links to atopic conditions have been established.


Full resolution is expected within two weeks of onset. 11% of patients develop a recurrence six weeks later.

Further reading and references

  1. Mahajan VK, Sharma NL; Erythema toxicum neonatorum. Indian Pediatr. 2010 Sep;47(9):793.
  2. Morgan AJ, Steen CJ, Schwartz RA, et al; Erythema toxicum neonatorum revisited. Cutis. 2009 Jan;83(1):13-6.
  3. Marchini G, Stabi B, Kankes K, et al; AQP1 and AQP3, psoriasin, and nitric oxide synthases 1-3 are inflammatory mediators in erythema toxicum neonatorum. Pediatr Dermatol. 2003 Sep-Oct;20(5):377-84.
  4. Yamasaki O, Manabe K, Morimoto A, et al; Pustular erythema toxicum neonatorum in two siblings born to a mother with group B streptococcus colonization. Eur J Dermatol. 2011 Mar-Apr;21(2):271-2. doi: 10.1684/ejd.2010.1229.
  5. Monteagudo B, Labandeira J, Cabanillas M, et al; Prospective study of erythema toxicum neonatorum: epidemiology and predisposing factors. Pediatr Dermatol. 2012 Mar-Apr;29(2):166-8. doi: 10.1111/j.1525-1470.2011.01536.x. Epub 2011 Nov 8.
  6. Ekiz O, Gul U, Mollamahmutoglu L, et al; Skin findings in newborns and their relationship with maternal factors: observational research. Ann Dermatol. 2013 Feb;25(1):1-4. doi: 10.5021/ad.2013.25.1.1. Epub 2013 Feb 14.
  7. Haveri FT, Inamadar AC; A cross-sectional prospective study of cutaneous lesions in newborn. ISRN Dermatol. 2014 Jan 20;2014:360590. doi: 10.1155/2014/360590. eCollection 2014.
  8. Liu C, Feng J, Qu R, et al; Epidemiologic study of the predisposing factors in erythema toxicum neonatorum. Dermatology. 2005;210(4):269-72.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 22 Jul 2028
  • 24 Jul 2023 | Latest version

    Last updated by

    Dr Colin Tidy, MRCGP

    Peer reviewed by

    Dr Pippa Vincent, MRCGP
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