Seborrheic dermatitis
Key points
- Seborrheic dermatitis is a skin condition characterized by loose, greasy or dry, white to yellowish scales, with or without associated reddened skin.
- Seborrheic dermatitis may involve the skin of the scalp, eyebrows, eyelids, nasolabial creases, lips, behind the ears, in the external ear, and the skin of the trunk, particularly over the sternum and along skin folds.
- The diagnosis is based on the appearance and location of the skin lesions.
- You can treat flaking and dryness with over-the-counter "dandruff" or medicated shampoos.
Alternative names
Dandruff; Seborrheic eczema; Cradle cap
Definition
Seborrheic dermatitis is a skin condition characterized by loose, greasy or dry, white to yellowish scales, with or without associated reddened skin. Cradle cap is the term used when seborrheic dermatitis affects the scalp of infants.
Causes, incidence, and risk factors
Seborrheic dermatitis may involve the skin of the scalp, eyebrows, eyelids, nasolabial creases, lips, behind the ears, in the external ear, and the skin of the trunk, particularly over the sternum and along skin folds. The cause is unknown.
Seborrheic dermatitis appears to run in families. Stress, fatigue, weather extremes, oily skin, infrequent shampoos or skin cleaning, use of lotions that contain alcohol, skin disorders (such as acne), or obesity may increase the risk.
Neurologic conditions, including Parkinson's disease, head injury, and stroke, can also be associated with seborrheic dermatitis. Human immunodeficiency virus (HIV) is also associated with increased cases of seborrheic dermatitis.
Cradle cap appears as thick, crusty, yellow or brown scales over the child's scalp. Similar scales may also be found on the eyelids, ear, around the nose, and in the groin. Cradle cap may be seen in newborns and small children up to the age of 3 years, and is a harmless, temporary condition.
Cradle cap is not contagious, nor is it caused by poor hygiene. It is not an allergy, and it is not dangerous. Cradle cap may or may not itch. If it itches, excessive scratching of the area may cause additional inflammation, and breaks in skin may cause mild infections or bleeding.
Symptoms
- Skin lesions
- Plaques over large area
- Greasy, oily areas of skin
- Skin scales - white and flaking, or yellowish, oily, and adherent - "dandruff"
- Plaques may include the scalp, eyebrows, nose, forehead, or ears
- Itching - may become more itchy if infected
- Mild redness
- Hair loss may also be associated with this disease
Signs and tests
The diagnosis is based on the appearance and location of the skin lesions.
Treatment
You can treat flaking and dryness with over-the-counter "dandruff" or medicated shampoos. Shampoo the hair vigorously and frequently (preferably daily). Loosen scales with the fingers, scrub for at least 5 minutes, and rinse thoroughly. Active ingredients in these shampoos include salicylic acid, coal tar, zinc, resorcin, or selenium.
Written and revised by
David Cohen, M.D.
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