Inhalant allergens include house dust mites, weed or grass pollen, animal danders and molds. In 5 to 45 percent of patients with eczema, applying these allergens to the skin elicits an eczema reaction. (In contrast, similar patch tests are usually negative in patients with respiratory allergy and healthy volunteers.) The level of IgE antibodies to inhalant allergens has also been shown to be associated with the severity of eczema.
The diagnosis of inhalant allergy can be made by prick skin testing or quantitative serum IgE levels against specific inhalant allergens. Prolonged avoidance of house dust mites in eczema patients known to be allergic to dust mites has been reported to result in improvement of their skin disease.
Avoidance measures include use of house dust mite-proof encasings on pillows, mattresses, and box springs; washing bedding in hot water weekly; removing bedroom carpeting; and decreasing indoor humidity levels.