The exact cause of neonatal toxic erythema is not known, but it has been speculated that it may be related to allergies or food, or that it may be related to the co-existence of microorganisms on the skin, and more recently it has been suggested that neonatal toxic erythema may be a localised immune response related to the maturation and development of the immune system. The condition usually resolves spontaneously within a week or so and parents need not worry too much about it.