Hi, I'm Dr. Roy Benaroch. I'm a pediatrician in private practice near Atlanta, Georgia, in Roswell, and we're here on About.com to talk about types, causes, treatment and prevention of heat rash in infants and children.Heat rash is also called 'prickly heat' or miliaria. The most common type is called miliaria rubra. This is red, usually little red bumps, especially in warm areas of the skin, like the folds of the neck. There's another variety called miliaria crystallina that looks like clear bubbles. Either one is cause by warm skin, especially in humid environments.The rash usually improves if you keep the skin cool and keep clothes from bunching up in the neck area. It can be treated just with observation and cooling, or topical hydrocortisone may help if the rash is uncomfortable. Heat rashes are best prevented by keeping the skin cool, and avoiding clothes that fit tightly or bunch up around the neck and armpits.