Erythema toxicum is a very common rash in infants. It appears in up to half of newborns carried to term, usually between day 2-5 after birth.

The rash is composed of small pustular lesions, each on a separate reddened base.

At times the appearance can raise concern that the rash could be due to herpes simplex, however the latter generally has a more clustered and vesicular appearance.

In uncertain cases, a scraping of a lesion can be done and the fluid examined under the microscope. Herpes lesions will have a positive direct fluorescent antibody test. The fluid from erythema toxicum lesions will show many eosinophils.

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  .:Erythema neonatorum toxicum Adapted from Dermatology Atlas.^[1]

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  .:Erythema neonatorum toxicum Adapted from Dermatology Atlas.^[1]
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  .:Erythema neonatorum toxicum Adapted from Dermatology Atlas.^[1]

The cause of erythema toxicum is unknown, but it is thought to be a benign condition that causes no discomfort to the infant and the rash will generally disappear spontaneously in about 2 weeks.

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• Photo at University of Iowa

Template:Certain conditions originating in the perinatal period