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Echinacea Not Effective for the Common Cold

Results of this large randomized controlled study showed no benefit for either prevention or treatment.

The herbal remedy echinacea is a popular but unproven treatment for the common cold. In this trial from the University of Virginia, researchers examined the effects of three different extracts of Echinacea angustifolia root (the extracts had differing proportions of presumed active constituents).

A total of 437 healthy volunteers agreed to receive nasal inoculations of rhinovirus and were randomized to seven groups. Three groups received active echinacea extracts that started 1 week before virus challenge and continued until 5 days after; three groups received active extracts that started on the day of virus challenge; and one group received placebo before and after virus challenge. This design allowed the researchers to assess both prevention and treatment effects.

No significant differences were observed between echinacea and placebo groups in the incidence of microbiologically and serologically proven rhinovirus infection (about 85% in each group), in the incidence of clinical colds (about 60% in each group), or in mean symptom scores after virus inoculation.

Comment: This trial — supported by the NIH Center for Complementary and Alternative Medicine — provides compelling evidence that Echinacea angustifolia does not prevent or alleviate symptoms of the common cold. An editorialist, suggesting that enthusiasts of herbal remedies likely will call for additional studies (to examine different echinacea species, different viruses, or different extracts), implies that time and money would be better spent elsewhere.

— Allan S. Brett, MD

Published in Journal Watch General Medicine August 5, 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.

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• 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)