A growing number of Americans are allergic to at least one or more common allergy-causing substances, like dust mites, rye grass, and ragweed.

A nationwide health survey shows that 54 percent of Americans aged 6 to 59 had a positive skin allergy test to at least one of 10 common allergy triggers, known as allergens. A positive skin allergy test is a major risk factor for allergic diseases, including asthma, hay fever, and eczema.

Researchers say the rates of allergies to common triggers found in this survey, which was conducted from 1988 to 1994, were two to five times higher than those found in the previous survey in 1976-1980.

They say the results are consistent with other studies that suggest that the number of people with allergies in the U.S. is on the rise.

Read WebMD's "Allergies Are on the Rise, but Why?"

America: An Allergic Nation?

In the study, researchers analyzed data on skin allergy tests from more than 30,000 Americans aged 6 to 59.

Participants were tested for allergies to 10 common allergens using a skin prick test. Results showed that 54 percent had a positive skin allergy test to at least one allergen.

The most common reactions were to dust mites, rye grass, ragweed, and cockroaches. Based on these results, researchers estimate that more than 25 percent of Americans are sensitive to one or more of these four allergens.

The researchers tested for the following allergy triggers: dust mites, cockroaches, cats, rye, ragweed, bermuda, grass, Russian thistle, white oak, the fungus alternaria, and peanuts

Other findings of the study include:

People who had a positive skin allergy test to one allergen had allergies to an average of three to five allergens in total. The least common reactions were to peanut, which accounted for 9 percent of positive skin allergy tests. Men were more likely than women to test positive for allergies.

The results of the study appear in the August issue of the Journal of Allergy & Clinical Immunology.

Read WebMD's "Newly Diagnosed with Allergies? Start Here"

By Jennifer Warner, reviewed by Michael W. Smith, MD

SOURCES: Arbes, S. Journal of Allergy & Clinical Immunology, August 2005; vol 116; pp 377-383. News release, American Academy of Allergy, Asthma & Immunology.