Seborrheic Dermatitis (Dandruff, Cradle Cap, Nappy Rash)

What is Seborrheic Dermatitis?

Seborrheic dermatitis is an inflammatory skin disease where there is excessive production of skin oils with some flaking of the skin. It is a common skin condition seen in children, particularly infants where it is usually seen as cradle cap and sometimes as nappy rash. Seborrheic dermatitis can also occur in adults and may sometimes be broadly referred to as dandruff.

Where does seborrheic dermatitis occur?

Seborrheic Dermatitis Affected Areas

Seborrheic dermatitis usually affects the scalp and face but other areas, like the buttocks (especially in newborns) may also be affected. Seborrheic dermatitis is commonly known as dandruff when it affects the scalp of adults and cradle cap in infants and newborns. However not all cases of dandruff may be seborrheic dermatitis as a head fungus can either complicate a pre-existing dermatitis or be the sole cause of dandruff.

In some cases, both in adults and infants, seborrheic dermatitis may affect the entire case although this is rare.

Why does seborrheic dermatitis occur?

Causes of Seborrheic Dermatitis

There is no clear cause of seborrheic dermatitis. Genetic factors may be a contributing factor and the condition usually aggravates in certain climatic conditions and seasons like winter.

There is some indication that a mild fungal infection caused by the yeast, Pityrosporum ovale, may be the cause of seborrheic dermatitis. However it is still believed that this yeast complicates a pre-existing case of seborrheic dermatitis rather than causing it. In cases of severe dandruff and nappy rash, an yeast infection is the most likely cause of the aggravated seborrheic dermatitis.

What does seborrheic dermatitis look like?

Signs & Symptoms of Seborrheic Dermatitis

University of Utah Medical Library
University of Utah Medical Library

Seborrheic dermatitis can be clearly distinguished from other skin disorders due to its scaling appearance although it may at times be confused with psoriasis vulgaris. Seborrheic dermatitis characteristically affects the head, both in adults and infants, although it can extend behind the ear, to the corners of the eye and nose and rest of the face. It may extend as far down as the sternum (breast bone) and may be seen on the buttocks in infants (baby’s bottom). Seborrheic dermatitis is another common reason for nappy rash. When it occurs on the face or buttock, it may appear red and inflamed.

In more severe cases of seborrheic dermatitis, thick yellow crusts may form on the affected area. Peeling the crists may allow plasma (sticky clear tissue fluid) and blood to leak from the affected area. Seborrheic dermatitis is usually accompanied by an itch although itching may vary from mild to severe.

Many cases of seborrheic dermatitis is complicated by a skin fungus or skin yeasts. Severe itching may be experienced in these cases with small white specks of skin shedding when scratching.

How is seborrheic dermatitis treated?

Treatment of Seborrheic Dermatitis

In cases where a fungal infection of the skin is present, treatment should first focus on eradicating the skin fungus. An antifungal cream or shampoo is used for a few weeks. An emollient and hydrocortisone cream or lotion may be applied to reduce the severity of the seborrheic dermatitis itself.

In milder cases, a salicylic acid cream or shampoo is usually effective in treating the condition until it resolves. An emollient should be used to maintain the barrier function of the skin.

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