Echinacea Has No Effect on Colds

NEW YORK (Reuters Health) - Taking the popular herbal agent Echinacea angustifolia does not help prevent the common cold, hasten its resolution, or reduce symptom severity, according to a report in this week's New England Journal of Medicine.

Some previous studies looking at the benefits of echinacea for treating the common cold have produced positive results, others have not. However, a variety of echinacea preparations are available and "only recently have there been attempts to standardize and characterize the material used in clinical studies," Dr. Ronald B. Turner, from the University of Virginia in Charlottesville, and colleagues note in their report.

In the current study, Turner's group assessed the outcomes of 437 volunteers who were randomly assigned to receive echinacea -- extracted with carbon dioxide, 60 percent ethanol, or 20 percent ethanol -- or an inactive "placebo".

The subjects were further randomized to receive the assigned agent before being exposed to a common cold virus or at the time of being exposed.

None of the echinacea preparations were any better than the placebo at preventing infection or at reducing symptom severity after infection. Moreover, the preparations had no significant effect on the volume of nasal secretions.

"Given the great variety of echinacea preparations, it will be difficult to provide conclusive evidence that echinacea has no role in the treatment of the common cold," the researchers comment. "Our study, however, adds to the accumulating evidence that suggests that the burden of proof should lie with those who advocate this treatment."

In a related commentary, Dr. Wallace Sampson, an editor of the Scientific Review of Alternative Medicine, notes that "unless some obscure protocol violation occurred, the trial results are real."

SOURCE: New England Journal of Medicine, July 28, 2005.