The term eczema, or dermatitis, is used to describe many conditions that can cause the skin to become inflamed or irritated. It can happen to adults or children and occur anywhere on the body but it is most common on the face, knees, hands, or feet. Eczema can cause the skin to become itchy and develop rashes that may ooze or crust over. The skin can become dry, thick or scaly. The first step in symptom management in adults is to determine the cause of eczema so that the right treatment approach can be found.

Genetics

There is currently no known cause of eczema, but it appears to run in families. The risk increases if conditions such as asthma or hay fever also occur in family members, states the National Institute of Arthritis and Musculoskeletal and Skin Diseases. Individuals with eczema appear to have low levels of a protein called cytokine, which helps the immune system function properly. Low levels of this chemical may cause the immune system to over-respond, leading to inflammatory skin conditions.

Pollution

The National Eczema Association for Science and Education states that individuals who live in urban areas and developed countries tend to have higher rates of eczema. It may be that exposure to certain irritants found in these areas can trigger eczema. Pollutants, industrial strength chemicals, paints and other substances may set off an allergic reaction that may eventually become eczema.

Skin Irritants

While most cases of eczema occur with no known cause, some forms, such as contact or seborrheic dermatitis, occur after a one-time or long-term exposure to known irritants, according to the American Academy of Dermatology. This includes battery acid, poison ivy, yeast and nickel (in those who are allergic to nickle). This reaction tends to occur more frequently in individuals with diseases that compromise the immune system.

Defects in the Skin

Much more research is needed to clearly understand why irritants trigger eczema in some people but not in others. A publication by the National Eczema Association suggests that a defect in the skin may play a role. Certain genes are responsible for proper skin development. This includes forming what is called the skin barrier, which helps to keep out irritants. If there are abnormalities in these genes, the skin barrier may not form correctly, which can allow substances to get into the skin and contribute to eczema.