BOSTON -- Americans spent $155 million on products that contained the herb echinacea last year, according to experts. Many take it to prevent the common cold or to lessen the symptoms from the virus -- but a new study questions whether it works.

Second only to garlic, echinacea is one of the best-selling medicinal herb in America. People like Gary Kracoff, a pharmacist at Johnson Drug in Waltham, Mass., take it to ward off a cold, reported WCVB-TV in Boston.

"My kids have been brought up that when they come home and feel a cold coming on, they ask for the echinacea," he said.

But a new government-funded study, published in this week's issue of the New England Journal of Medicine, suggests that the herb doesn't ward off colds.

In the study, researchers at the University of Virginia School of Medicine gave 400 volunteers one of three lab extracts of echinacea or a placebo. The participants also got inoculated with the most common type of cold virus -- some at the same time they started the treatment and others seven days later.

Researchers found that about 80 percent of those in the study got the infection, and it didn't matter whether they had taken echinacea.

Infectious disease specialists said the evidence is clear.

"There's now a good study out there, very well done, appearing in a peer-reviewed journal that shows that it did not work," said Dr. Michael Lew, of Newton-Wellesley Hospital in Newton, Mass.

The study also found that echinacea didn't lessen the length or the severity of symptoms. But Kracoff said the type of echinacea used in the study isn't the kind found in most products and wasn't used at the appropriate dose.

"If you're taking a high blood pressure medicine and you're supposed to take 50 milligrams and you take 5 milligrams, does that mean that mean that drug is totally ineffective? No. It's ineffective at that dose," he said.

Others say that, despite the study, there's no harm in taking echinacea if you want to.

"I would categorize it in the same category as chicken soup. And if you believe in chicken soup, you can have just about the same kind of belief about taking echinacea," Lew said.

In an editorial that accompanies the study, a Stanford University researcher pointed out this is the latest in a series of studies that fail to prove echinacea works and suggested that the National Institutes of Health should stop wasting money trying to prove otherwise.

There are at least three other large clinical studies under way looking at effectiveness of echinacea.

Additional Resources:

• Study Abstract
• Editorial Extract