Seborrheic dermatitis is a chronic skin condition that causes a red, scaly, itchy rash. It can appear as a mild, white scaling or a yellowish greasy or reddish scaly rash. Most commonly affected areas are along the hairline, in and behind the ears, on the eyebrows, around the nose, and on the chest.
Dandruff is a type of seborrheic dermatitis where there is a scaling of the skin on the scalp. The area can be dry or oily and is sometimes itchy.