Echinacea No Good for the Common Cold

Dec. 21, 2010— -- Taking echinacea had no significant effect on the duration or severity of the common cold, according to the results of a randomized, blinded trial.

The average duration of symptoms was 6.34 days in patients taking echinacea in a blinded fashion and 6.76 days in patients who knew they were receiving the herb, according to Dr. Bruce Barrett of the University of Wisconsin in Madison and colleagues.

There also was no significant difference in cold severity as assessed by the Wisconsin Upper Respiratory Symptom Survey, the researchers reported Dec. 21 in Annals of Internal Medicine.

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"However, the trends were in the direction of benefit, amounting to an average half-day reduction in the duration of a week-long cold, or an approximate 10 percent reduction in overall severity," they noted.

Indigenous peoples of North America used echinacea for numerous illnesses, and it has been used therapeutically for nearly a century in Germany where plant-based medicine has long been widely practiced. Extracts of the plant are thought to boost immunity.

Many studies to date have attempted to clarify echinacea's cold-fighting effects, and although some early trials showed positive results, most were manufacturer-sponsored and their quality was questionable, according to Barrett and colleagues.

More recent trials have yielded conflicting results, and meta-analyses, which review data from multiple studies, have failed to provide clear results or interpretations.

To address whether echinacea extracts could significantly influence the outcome of upper respiratory tract infections, Barrett and colleagues enrolled 719 patients in a trial conducted under the auspices of the National Institutes of Health's National Center for Complementary and Alternative Medicine.

Patients were randomized to four groups: echinacea (10.2 g of dried echinacea root during the first day and 5.1 g per day for four additional day) taken either knowingly or not knowing whether it was echinacea or placebo, placebo, or no treatment at all.