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Contact dermatitis

Author: Dr Amanda Oakley, Dermatologist, Hamilton, New Zealand, 2012.

What is contact dermatitis?

Contact dermatitis (also called contact eczema) refers to a group of skin disorders in which the skin reaction is due to direct contact with the causative agent. The term dermatitis implies that the outside layers of skin are affected. It can be acute (a single episode) or chronic (persistent). Dermatitis is nearly always itchy.

Contact dermatitis includes several entities.

Contact dermatitis is sometimes mixed in origin, particularly when it is resulting in hand dermatitis. Contact dermatitis is the most common cause of occupational skin disease, and is particularly common in cleaners, healthcare workers, food handlers and caterers and hairdressers. It can even occur in people using computers (computer mouse dermatitis).

What does contact dermatitis look like?

The appearance of contact dermatitis is highly variable. It may affect any area of the body and may be any shape (linear, round, polygonal, irregular). Affected skin may have any of the following features.

Secondary changes may include:

How is the diagnosis of contact dermatitis made?

Contact dermatitis is usually identified after taking a careful history.

The various forms of contact dermatitis may appear similar to each other. They may be distinguished by the following features.

Patch tests are important to identify contact allergens in any severe or persistent case of contact dermatitis. An Open application test may also be recommended.

How is contact dermatitis treated?

Once the causes of contact dermatitis are identified, it is important to avoid direct contact with them. But whatever the cause of the dermatitis, the barrier function of the skin has been damaged and further dermatitis may occur if exposed to irritants.

The rash can be treated with a short course of topical corticosteroid creams. Apply emollients frequently while the rash is active and for some weeks afterwards as the normal skin barrier function is restored.

Severe contact dermatitis may be treated with a short course of systemic corticosteroids, e.g. oral prednisone. Occasionally, for chronic contact dermatitis, phototherapy may be tried, or immunosuppressive agents such as methotrexate, ciclosporin or azathioprine may be prescribed.

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Watch Dr Amanda Oakley presenting "Skin lesion photography" at The Australasian Skin Cancer Congress.

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