Erythema toxicum is a rash of newborn babies.
“Erythema Toxicum Neonatorum” is the complete, horrible name medical pedants give to it, guaranteed to impress and scare any parent. It means “toxic redness of the newborn”. It is certainly red, usually discrete but occasionally florid, but certainly not toxic. The name should be changed to Erythema Jocularis because it is a common, jokey skin condition that appears on some babies in the first few days of life, lasts about seven to ten days and mostly disappears by two weeks.
Erythema toxicum has been known to doctors for centuries. Unsurprisingly, it was first described in the Middle East by the Mesopotamians, who believed that it represented a cleansing mechanism against the mother’s dirty blood. One feels certain that if we had access to ancient Indian or Chinese medical treatises, we would see similar descriptions from these societies, who were reading and writing while most other peoples at the time were living in filth.
The Europeans finally got into the act in 1472, when a German physician, Bartholomaeus Metlinger, “discovered” it and associated it with a reaction to meconium on the baby’s skin. Wrong again, but it’s interesting how readily these old-timers, all male, rushed to blame it on things considered contaminated, such as the mother’s blood, faeces and so on.
The idea of pollution continued into the 20th century, when the name erythema toxicum neonatorum was first used by an Austrian, Dr Karl Leiner, in 1912. This goodly gentleman continued the pollution emphasis. He believed the rash was caused by enterotoxins or poisons from the gut. He got it quite wrong, another in the long line of medical doctors who make up their own theories about an illness and manage to convince people for years that they know what they are talking about. It should be called Leiner’s folly because it worries parents unnecessarily.
Fortunately, it is uncommon in local babies. I would have seen erythema toxicum in about half of all babies born in the hospitals in Baltimore, but not in T&T. Because it is relatively unknown here, it can be easily misdiagnosed as heat rash or acne, infection, including chickenpox, and, worryingly, herpes.
Its exact cause is unknown, but we now think it is related to activation of the baby’s immune system. That is a good thing. It seems that bacteria activate the immune system when they enter hair follicles for the first time. This is part of a normal process in which bacteria from the environment, ideally from the mother’s vagina, mouth and skin, and not from the obstetrician or paediatrician or delivery room, start to grow on a baby’s skin.
The rash consists of small yellowish, fluid-filled bumps surrounded by an irregular reddish patch, the erythema (see picture). Most lesions are temporary, often disappearing within a few hours and reappearing elsewhere. Lesions may be sparse or numerous, clustered in several sites or widely dispersed over much of the body surface. They can occur on any body part but never on the palms of the hands and soles of the feet. It usually appears within the first few days of life, certainly in the first week. The rash often appears and disappears, reforming in new areas within hours. It usually disappears within seven to 14 days but can return on and off up to six weeks of age. It never leaves a mark. As is usual with most self-healing “illnesses” in children, the application of any sort of cream or plant exudate is the cause of celebration by well-meaning family members and medical attendants.
Those small, yellowish bumps surrounded by a red zone can look quite alarming but don’t cause any discomfort to the baby and don’t have any long-term effects. It seems to be very rare in premature babies and is more common in males and, as you would expect, appears more frequently if the baby is fed formula.
You should get concerned and consult a paediatrician if the rash lasts longer than two weeks straight without appearing or disappearing, if it bleeds or oozes or, of course, if the baby goes off its feeding, appears lethargic or develops a fever.
The primary challenge with Erythema Toxicum lies in its potential for misdiagnosis. This can lead to unnecessary investigations and treatments and cause significant parental and caregiver anxiety. Yet it is the most harmless of rashes.
