under a microscope. Some of these tests may be ordered if the diagnosis is unclear. Treatment Erythema toxicum neonatorum resolves without treatment, typically within one or two weeks. There are no associated systemic symptoms or long-term consequences of the rash. History The rash of erythema toxicum neonatorum has been described by doctors for centuries. Ancient Mesopotamians believed that it represented a cleansing mechanism against the mother's blood. Later physicians believed that it was caused by the skin's response to meconium. The name erythema toxicum neonatorum was first used by Dr. Karl Leiner in 1912 because he believed that the rash was caused by enterotoxins. Although Leiner's hypothesis was incorrect and the rash is not actually caused by toxins, the medical community continues to call the rash erythema toxicum neonatorum. References External links Eosinophilic cutaneous conditions Neonatology