Colloidal oatmeal is finely ground oatmeal dissolved in water.
It forms a protective film on the surface of the skin, locking in moisture and preventing dryness and flaking. It also helps alleviate skin irritation.
It can come in your shampoo but you can make some at home to stop that itch in your scalp.
Wrap a handful of oats in a muslin cloth, hold the cloth beneath a tap of running lukewarm water, collecting the water runoff in a jug pour the oatmeal water gently and evenly over the scalp