Unlike cars, babies don't come with instruction manuals. They don't come with warning lights, either. Being a new parent is a learning experience, and it isn't always easy. But it is easy to worry about something that seems abnormal, like a rash, on your newborn baby. Keep in mind, however, that rashes -- and a number of other conditions -- are incredibly common, and you probably have nothing to worry about. The most common rash on newborns is called erythema toxicum; you might be surprised to learn that it actually affects about half of all newborn babies [source: Rauch].

Don't worry, it sounds a lot worse than it is. Erythema toxicum may affect a majority of newborns, but it's also completely harmless. Most new parents don't know that, which can cause a bit of unnecessary distress.

If you've seen an outbreak of erythema toxicum, you'll understand the concern. It doesn't exactly look like a harmless rash. Educating yourself about the symptoms and possible treatments will help put your mind at ease. And remember, physicians can easily diagnose erythema toxicum.

Erythema toxicum has been affecting newborns for a long time. One medical book from 1826 talks about the respect nurses used to give the rash. It was such a common condition that they often blamed the absence of it for other infant ailments [source: Finlay & Bound]. We know now that isn't the case -- but to be honest, we don't know much more about the condition than they did in 1826. Fortunately, the rash doesn't produce any negative side effects or cause any discomfort.

Keep reading to find out about the symptoms of erythema toxicum.