Have you ever had a red, itchy rash on your skin? Then you've had dermatitis. Dermatitis is an irritation or swelling of the skin.
There are lots of different kinds of rashes — some have bumps, some have blisters, and some are dry and scaly. They can be caused by a chemical (like a soap) that irritates your skin, or happen when you touch something you're allergic to (like poison ivy). Skin conditions like eczema or dandruff also can cause a rash.