Natural supplement, echinacea, may reduce common-cold duration by only half a day

The study, published in this month's Annals of Internal Medicine, involved echinacea, a wild flower (also known as the purple coneflower) found in meadows and prairies of the Midwestern plains. The supplement is sold in capsule form in drug and retail stores. Dried echinacea root has been used in homemade remedies such as teas, dried herb and liquid extracts.

The randomized trial involved more than 700 people between 12 and 80 years old. The subjects, all of whom had very early symptoms of a cold, were divided into four groups. One group received no pills, a second group received what they knew was echinacea, and a third group was given either echinacea or a placebo, but they did not know which. Participants recorded their symptoms twice a day for the duration of the cold, up to two weeks.

According to Bruce Barrett, the lead researcher and an associate professor of family medicine, patients receiving echinacea saw the duration of their cold reduced by seven to 10 hours. But he says this was not considered a significant decrease.

"Trends were in the direction of benefit, amounting to an average half-day reduction in the duration of a weeklong cold or an approximate 10 percent reduction in overall severity," he says. "However, this dose regimen did not make a large impact on the course of the common cold, compared either to blinded placebo or to no pills."

Barrett says a larger trial involving people who have found echinacea useful may help provide more answers. He adds that there were no side effects seen, so there is no reason that cold sufferers should stop using echinacea if they think it helps them.

"Adults who have found echinacea to be beneficial should not discontinue use based on the results of this trial, as there are no proven effective treatments and no side effects were seen," says Barrett.