Seborrheic dermatitis (seb-o-REE-ik der-muh-TI-tis) is a common skin disorder that mainly affects your scalp, causing scaly, itchy, red skin and stubborn dandruff. In infants, seborrheic dermatitis of the scalp is known as cradle cap. Seborrheic dermatitis can also affect your face, upper chest, back and other areas of your body that have many oil (sebaceous) glands.
Seborrheic dermatitis doesn’t affect your overall health, but it can be uncomfortable and cause embarrassment when it develops on visible parts of your body. It isn’t contagious, and it’s not a sign of poor personal hygiene. Seborrheic dermatitis tends to recur, but you may be able to manage flare-ups by recognizing its signs and symptoms and by using a combination of self-care steps and over-the-counter (nonprescription) medications.