1. Home>
2. Specialties>
3. Infectious Diseases>
4. Summary and Comment

Echinacea Ineffective in Rhinovirus Trial

Echinacea, a popular alternative therapy for the common cold, showed no effect — prophylactic or therapeutic — in a recent rhinovirus trial.

Echinacea is a popular alternative therapy for the common cold, despite very limited data showing clinical benefit. Now, in a large, well-designed, controlled trial supported by the NIH, researchers have studied the effect of this herb in a standard experimental rhinovirus infection model.

The investigators randomized 437 healthy young adult volunteers in Virginia to take either placebo or one of three standardized Echinacea angustifolia root extracts (differing in their concentrations of plant polysaccharides and alkamides) for the 7 days before and the 5 days after challenge with rhinovirus type 39. None of the preparations had any effect either prophylactically or therapeutically on the development of rhinovirus infection, the development or course of clinical illness, the severity of any cold symptoms, or the concentrations of interleukin-8 or polymorphonuclear-leukocyte in nasal-lavage fluids.

Comment: This study provides conclusive evidence that these well-characterized echinacea preparations had no effect on rhinovirus 39 infections. Proponents will no doubt argue that other echinacea preparations might have activity, or that the preparations used in this trial might be active against other viruses. However, as noted by an editorialist, excluding potential efficacy is more difficult than proving real efficacy, and further study of echinacea requires solid scientific evidence demonstrating clinical benefit. Unless such evidence is forthcoming, we must conclude that echinacea has no benefit for upper respiratory infections.

— Richard T. Ellison III, MD

Published in Journal Watch Infectious Diseases August 19, 2005

Citation(s):

Turner RB et al. An evaluation of Echinacea angustifolia in experimental rhinovirus infections. N Engl J Med 2005 Jul 28; 353:341-8.

• Original article (Subscription may be required)
• Medline abstract (Free)

Sampson W. Studying herbal remedies. N Engl J Med 2005 Jul 28; 353:337-9.

• Original article (Subscription may be required)
• Medline abstract (Free)