is a common, inflammatory skin condition that causes flaky, white to yellowish scales to form on oily areas such as the scalp or inside the ear. It can occur with or without reddened skin. Cradle cap is the term used when seborrheic dermatitis affects the scalp of infants.
Causes, incidence, and risk factors
Seborrheic dermatitis is thought to be due to a combination of an over production of skin oil and irritation from a yeast called Malessizia. 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 may be associated with seborrheic dermatitis. Human immunodeficiency virus (HIV) has also been linked to increased cases of seborrheic dermatitis.
Usually seborrheic dermatitis forms where the skin is oily or greasy. Commonly affected areas include the scalp, eyebrows, eyelids, creases of the nose, lips, behind the ears, in the outer ear, and middle of the chest. Seborrheic dermatitis in infants or young children, also called cradle cap, is a harmless, temporary condition. It 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 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.
In general, symptoms of seborrheic dermatitis include skin lesions, greasy or oily areas of skin, scales or "dandruff", itching, redness or hair loss.
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. 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 could include salicylic acid, coal tar, zinc, ketoconazole, selenium or others. Prescription shampoos or medications may be prescribed for severe cases. Seborrheic dermatitis may improve in the summer, especially after outdoor activities.
Seborrheic dermatitis is a chronic (life-long) condition that can be controlled, not cured, with treatment. It often has extended inactive periods followed by flare-ups. A more extreme form of this condition overlaps with psoriasis of the scalp and is called sebo-psoriasis.