In the winter months, with the incidence of colds on the rise, many turn to the herbal supplement echinacea in the hopes of reducing their symptoms. But a new study adds to recent research suggesting these efforts have no real impact in lessening illness.

In the study, people with cold symptoms who took echinacea said their symptoms, on average, cleared up 7 to 10 hours sooner than those who did not — an effect so small it may simply have been because of random chance, the researchers said.

"Illness duration and severity were not statistically significant with echinacea compared with placebo," said the researchers from the University of Wisconsin in the study. "These results do not support the ability of this dose of the echinacea formulation to substantively change the course of the common cold."

The study followed 719 patients with cold symptoms in Wisconsin. Some were given echinacea or a placebo but not told which they had. Others received echinacea and knew they were taking it, and others were given nothing. Patients recorded their symptoms over the next week.

Echinacea comes from the purple coneflower. Supplements use various formulas made from different parts and species of the plant. Sales of echinacea in the United States are above 100 million dollars per year, according to the Nutrition Business Journal.

Because it is a natural, herbal product, echinacea has gained some popularity. However, its widespread use for treating colds in the U.S. is relatively recent, and questions have persisted over whether it actually provides positive effects. The flower is also known to trigger some mild allergic reactions.

A number of studies have been conducted on echinacea during the past 10 years, with no clear answer as to whether taking echinacea can reduce the chances of catching a cold or shorten one's duration. But what has emerged from the studies is the fact that someone buying echinacea from the store to treat his or her cold or to prevent one is likely wasting money.

"I think that echinacea might prevent colds," said Dr. James A. Taylor, of the University of Washington's Child Health Institute, who was not involved with the new study. But because the products vary, the problem is selecting a one that actually works from the many that don't.

"We are currently working to identify specific preparations with biologic activity, Taylor said. "I would tell a parent that some echinacea might prevent colds, but that there is no definitive evidence of a preventive effect that has been published to date."

He said that cold sufferers, like the people in the study, who take echinacea to heal faster were probably trying in vain.

"In terms of treatment of colds, this is a well done study, and the results are consistent with other rigorously conducted trials on treatment of colds in which little, if any, beneficial effect has been found," Taylor said.

Dr. Wallace Sampson, a former clinical professor of medicine at Stanford University School of Medicine, has been critical of funding echinacea studies, saying that the money could be better spent elsewhere.

"There was no more reason to test [echinacea] for colds than for any other randomly selected condition," he told MyHealthNewsDaily, pointing out that in folk medicine, echinacea was used for treating 15 or 20 different, unrelated conditions.

While Native Americans used echinacea to cure a number of ailments, Sampson said, those groups lacked a modern understanding of disease causes and courses. "Add to that, the unlikelihood of accurate translation of Indian dialects," by English-speaking people, he said, "and one can imagine some of the distortions that resulted."

Despite their results, researchers are skeptical their new study will do much to change people's opinions of echinacea's effects, and Taylor agreed.

"I have found that people are pretty polarized by echinacea, either believing that it really works or it really doesn't," Taylor said. "Given these fairly dogmatic beliefs, there is a little something in the results of this study for people on both sides."

Pass it on: Echinacea doesn't help treat colds.

This article was provided by MyHealthNewsDaily, a sister site to LiveScience.