Seborrheic dermatitis is a common, chronic or recurrent skin condition that causes red patches covered with large, greasy, flaking yellow-gray scales, and persistent itch. Seborrheic dermatitis occurs most often on the scalp, face (especially on and around the nose, eyebrows, and eyelids), ears, upper chest and back.   A milder form of seborrheic dermatitis is common dandruff.