CHICAGO -- Echinacea is one of the most commonly used herbal remedies in the United States, and many adults use it to prevent and treat colds.

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But a new study says parents who treat kids' colds with echinacea will find the colds are no better, and the kids may get a rash.

The study, published in Wednesday's issue of the Journal of the American Medical Association, is one of the largest yet to question the value of the popular but unproven herbal remedy.

According to the article, the average child has six to eight colds each year, each lasting seven to nine days.

Researchers from the University of Washington in Seattle prescribed either echinacea or a placebo to 407 children ages 2 to 11. The kids were treated at the onset of cold symptoms and continued for a maximum of 10 days.

They found echinacea extract worked no better in battling colds than a dummy preparation.

Not only did the cold symptoms not improve, but mild skin rashes occurred in 7 percent of kids treated with echinacea. Rashes were found in less than 3 percent of kids given the fake preparation.

The researchers said further studies using different echinacea formulations, doses, and dosing frequencies are needed to confirm the results.

An official of an independent group that studies herbs suspects the echinacea was not given soon enough after symptoms appeared.

Journal of the American Medical Association