Eczema Causes
No one knows what causes eczema. Studies aiming to identify causes of the disease are underway.
Children of parents who have allergic diseases are more likely to develop eczema than children of parents who do not. For this reason, many scientists believe genes may contribute to causing eczema. Recent research has identified mutated forms of specific genes that may be involved.
Scientists also believe environmental factors play a role. Research conducted at NIAID has demonstrated how exposing the skin of mice to a chemical called isocyanate induces eczema. Exposing laboratory-based cell cultures of human skin to this class of chemicals induced the same abnormalities that researchers observed in the mice. Other studies in large populations have found associations between the number of new cases of eczema in a region and long-term exposure to air pollutants—namely soot, sulfur dioxide, nitrogen dioxide and carbon monoxide.
The bacteria, fungi, viruses and other microorganisms that live on the skin—collectively called the skin microbiome—may also play a role in eczema development. Normally, the skin microbiome supports the skin in preventing infection and water loss, among other healthy functions. Researchers have found that the composition of the skin microbiome is very different in people with eczema compared to healthy people. Notably, people with eczema have smaller proportions of microbes that promote healthy skin. While some research suggests that a disturbed skin microbiome may precede the development of eczema, this has not been seen in all studies. It remains unclear whether changes to the skin microbiome are a cause or an effect of the abnormal skin immune function and defective skin barrier found in people with eczema.
To help clarify the causes of eczema, the NIAID-funded SUNBEAM study is examining the roles and interrelationships of genetic, environmental, clinical, and biological factors in the development of eczema and other allergic diseases among 2,500 children from birth to age 3 years.
In addition, an exploratory study at NIAID is comparing differences between adults with and without eczema in the substances their skin makes when breaking down chemicals. Researchers plan to use what they find to identify environmental factors that affect the breakdown of specific chemicals in the skin.
Eczema Triggers
Many environmental substances and characteristics can cause eczema to worsen. These triggers vary from person to person and may include:
- Pollen
- Mold
- Dust mites
- Animals
- Cold, dry air
- Respiratory viruses including influenza
- Fumes from wildfires, automobiles, and certain factories
- Certain chemicals, including fragrances and dyes
- Rough fabric such as wool
Emotional factors such as stress also can trigger eczema flares, as can certain foods among people with food allergy.