Eczema, also known as atopic dermatitis, develops when a person’s immune system becomes sensitized to proteins from a source inside or outside the body. The immune system becomes overactive and sets off inflammatory processes that attack the skin.

Most scientists believe eczema is probably caused by a combination of inherited and environmental factors that affect the immune system in the skin. Still, no one has identified why some people develop eczema and some people don’t.

Risk Factors for Eczema

It is important to note that while science is good at finding correlations, or apparent relationships, between factors and disease, correlation does not prove the factor causes the disease. Many risk factors for eczema have been identified and are being studied, but none have been pinpointed as the cause of eczema.

Age is a factor in the development of eczema. Younger children are more at risk for developing eczema than older people. Many children with eczema will outgrow this condition, but they may always have more sensitive skin.

Hereditary Factors

People are more likely to develop eczema if a close relative also has eczema. People with eczema are also more likely to develop other immune-related conditions, including asthma and food allergies. These three related conditions — allergies, eczema, and asthma, known as the “atopic triad” or “atopic march” — tend to run in families. Approximately 70 percent of those diagnosed with atopic dermatitis have a family history of atopic conditions.

One gene that has been identified as a significant influence in the development of eczema is the gene that controls the production of filaggrin. Filaggrin is a protein that helps form a protective barrier on the outer layer of skin. Studies have shown that those with the genetic variant resulting in lower levels of filaggrin are more likely to develop eczema due to a compromised barrier of the skin. Abnormal filaggrin levels allow external factors to irritate the skin more easily.

Approximately 35 percent of people with food allergies also have eczema. Genes that influence skin absorbency may contribute to eczema. A new theory about the development of food allergies suggests the immune system becomes sensitized to foods when babies receive early exposure to the foods via their skin. If babies with vulnerable skin are kissed and touched by people with food on their hands or mouths, the theory suggests, perhaps the proteins absorb into the baby’s skin, and the immune system interprets the food proteins as dangerous invaders.

Environmental Factors

Children born to older mothers appear to be more likely to develop eczema.

Living in developed countries and urban areas also seems to increase the risk of developing eczema. This may be due to environmental exposure.

Those who live in colder, drier climates appear to be more likely to develop eczema. This is because the dry air takes moisture from the skin, leaving the skin with small cracks that make it more sensitive to the environment.

Can Eczema Be Prevented?

Since scientists are not yet sure why some people develop eczema, there is no known way to prevent it. Hereditary factors that seem to raise the risk for eczema are beyond anyone’s control.

Factors that may reduce the risk for developing eczema include:

• Using moisturizers daily to maintain a healthy skin barrier, starting in early life
• Being raised with pets or livestock
• Attending day care before age 2
• Normal exposure to germs in childhood

Stress is not believed to cause eczema. However, the chemicals the body produces in response to stress can also worsen symptoms of eczema. For some people, stress is a trigger for eczema flares.

Condition Guide

• Eczema — An Overview
• Eczema Symptoms
• Eczema — The Path to Diagnosis
• Eczema vs. Psoriasis: Are They One and the Same?
• Treatments for Eczema
• Types of Eczema
• Conditions Related to Eczema