What is 'dermatitis'?: Skin rashes tend to come out of the blue. One day you may notice an inflamed or itchy legion on your skin, and not even know what caused it. So what does cause skin rashes? Often times it can just be a build-up of dry skin, an allergic reaction or something else that can be easily treated. However, there is always a change that it can possibly be something more serious, which is why if you develop a rash you should take the necessary measures to make sure that it isn’t something seriously health threatening. Watch what our expert has to say about skin rashes and get in the know on how to care for your body's largest organ.