Many common childhood illnesses are accompanied by pustules, red spots or wheals.

But not all skin rashes are treated the same way.

Here's what parents need to know.

If your young child develops a rash, a likely cause is a common childhood illness.

The child should be examined by a doctor for a diagnosis and treatment, of course, but here's how to tell the difference between scarlet fever, chickenpox, fifth disease, three-day fever and measles rashes.

> Scarlet fever

Scarlet fever starts with a red, bumpy rash around the armpits and groin.

The small bumps, about the size of a millet seed or pinhead, spread over the entire body with the exception of the area around the chin and mouth.

"The rash has a velvety appearance, but doesn't itch," says Jakob Maske, spokesman for the Cologne-based Professional Association of Paediatricians (BVKJ) in Germany.

Unlike rashes caused by measles or rubella, a scarlet fever rash blanches when pressed.

It fades completely after one to three weeks, and then the skin peels.

"Scarlet fever is often accompanied by a sore throat and fever," says paediatrician Dr Hermann Josef Kahl.