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Overview of Dermatitis

by Karen McKoy, MD, MPH

Dermatitis (eczema) is inflammation of the upper layers of the skin, causing itching, blisters, redness, swelling, and often oozing, scabbing, and scaling.

  • Known causes include dry skin, contact with a particular substance, certain drugs, varicose veins, constant scratching, and fungal infections.

  • Typical symptoms include a red itchy rash, blisters, open sores, oozing, crusting, and scaling.

  • The diagnosis is typically based on symptoms and confirmed by results of patch tests or skin samples or the presence of suspected drugs, irritants, or infection.

  • Avoiding known irritants and allergens reduces the risk of dermatitis.

  • Treatment depends on the cause and the specific symptoms.

Dermatitis is a broad term covering many different disorders that all result in a red, itchy rash. The term eczema is sometimes used for dermatitis. Some types of dermatitis affect only specific parts of the body, whereas others can occur anywhere. Some types of dermatitis have a known cause, whereas others do not. However, dermatitis is always the skin's way of reacting to severe dryness, scratching, an irritating substance, or an allergen. Typically, that substance comes in direct contact with the skin, but sometimes the substance is swallowed. In all cases, continuous scratching and rubbing may eventually lead to thickening of the skin (lichenification).

Dermatitis may be a brief reaction to a substance. In such cases, it may cause symptoms, such as itching and redness, for just a few hours or for only a day or two. Chronic dermatitis persists over a period of time. The hands and feet are particularly vulnerable to chronic dermatitis, because the hands are in frequent contact with many foreign substances and the feet are in the warm, moist conditions created by socks and shoes that favor fungal growth.

Chronic dermatitis may represent a contact, fungal, or other dermatitis that has been inadequately diagnosed or treated, or it may be one of several chronic skin disorders of unknown origin. Because chronic dermatitis causes cracks and blisters in the skin, any type of chronic dermatitis may lead to bacterial infection.

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