Childhood rashes have a variety of causes, the most common of which are either bacterial or viral in nature, as cited by WebMD. Diaper rash, cradle cap and heat rash are also common in children and infants.
Bacterial rashes stem from certain childhood diseases, the most common of which are impetigo and scarlet fever, reports eMedicineHealth. Impetigo, a skin infection resulting from either the staphylococcal or streptococcal bacteria, is most often seen around the nose and mouth during warmer weather. Scarlet fever, most commonly seen in school children during the colder months, is a combination of strep throat and a moderate rash seen virtually everywhere except on the soles of the feet or the palms.
Viral rashes are a result of certain viral infections, including chicken pox, measles and rubella. The rash that results from chicken pox covers the entire body, and it presents as small blisters that are both extremely itchy and contagious. Measles produces a brown rash that starts on the face and spreads out to the rest of the body, usually subsiding in about a week. Rubella, a much milder illness than both chicken pox and measles, results in an itchy, pink rash that usually starts to dissipate in about three days, states eMedicineHealth.