Echinacea does not prevent colds

Reported by Susan Aldridge, PhD, medical journalist

While the herbal remedy echinacea may shorten the duration of a cold, it will not prevent your getting one.
Echinacea has long been a top-selling herb for treatment and prevention of colds. Researchers at the University of Munich have been looking at evidence for its efficacy. They found 16 clinical trials, 11 of them new and most comparing echinacea to placebo or no treatment. The most common formats of the remedy were pressed juice, alcohol suspension or tablets containing dried extract.

The participants in these trials had colds and flu. There was evidence that pressed juice could reduce the severity and duration of symptoms. However, none of the echinacea preparations could actually prevent colds and flu. Whether, in the light of this evidence, echinacea is worth the money is clearly debatable.

Source
The Cochrane Database of Systematic Reviews 2006 Issue 1