Treatment of the Common Cold with Unrefined Echinacea

A Randomized, Double-Blind, Placebo-Controlled Trial

  1. Bruce P. Barrett, MD, PhD;
  2. Roger L. Brown, PhD;
  3. Kristin Locken, BA;
  4. Rob Maberry, BA;
  5. James A. Bobula, PhD; and
  6. Donn D'Alessio, MD
  1. From University of Wisconsin—Madison, Madison, Wisconsin.

    Abstract

    Background: Echinacea preparations are widely used to treat the common cold.

    Objective: To assess the efficacy of dried, encapsulated, whole-plant echinacea as early treatment for the common cold.

    Design: Randomized, double-blind, placebo-controlled community-based trial.

    Setting: University of Wisconsin—Madison, Madison, Wisconsin.

    Participants: 148 registered students with common colds of recent onset.

    Intervention: An encapsulated mixture of unrefined Echinacea purpurea herb (25%) and root (25%) and E. angustifolia root (50%) taken in 1-g doses six times on the first day of illness and three times on each subsequent day of illness for a maximum of 10 days.

    Measurements: Severity and duration of self-reported symptoms of upper respiratory tract infection.

    Results: No statistically significant differences were detected between the echinacea and placebo groups for any of the measured outcomes. Trajectories of severity over time were nearly identical in the two groups. Mean cold duration was 6.01 days in both groups as a whole, 5.75 days in the placebo group, and 6.27 days in the echinacea group (between-group difference, −0.52 day [95% CI, −1.09 to 0.22 days]). After controlling for severity and duration of symptoms before study entry, sex, date of enrollment, and use of nonprotocol medications, researchers found no statistically significant treatment effect (adjusted hazard ratio, 1.24 [CI, 0.86 to 1.78]). Multivariable regression models assessing severity scores over time failed to detect statistically significant differences between the echinacea and placebo groups.

    Conclusion: Compared with placebo, unrefined echinacea provided no detectable benefit or harm in these college students who had the common cold.

    Article and Author Information

    • Acknowledgments: The authors acknowledge the Native American peoples who first brought echinacea to the attention of the world community. They thank the study participants and the research assistants who worked with them: Beth Amspaugh, Kira Conroy Williams, and Peter Jung; and Marijka Hambrecht, who very effectively managed the Web-based data collection tool. They thank Carlo Calabrese, John Frey, Jim Gern, Jack Gwaltney, Mike Fleming, Pat McBride, Mary Beth Plane, and Bill Scheckler for helpful comments. In addition, they thank Pam Manning, Chris Jensen, and Eric Zaltas at Shaklee Tecnica for their excellent work.

    • Grant Support: By the U.S. Department of Health and Human Services (Institutional National Research Service Award T-32 HP 10010-09 from the Health Resources and Services Administration [Dr. Barrett]), National Center for Complementary and Alternative Medicine at the National Institutes of Health (K23 AT00051-01 [Dr. Barrett]), and Shaklee Tecnica.

    • Potential Financial Conflicts of Interest: None disclosed.

    • Requests for Single Reprints: Bruce P. Barrett, MD, PhD, Department of Family Medicine, University of Wisconsin—Madison, 777 South Mills Street, Madison, WI 53715.

    • Current Author Addresses: Dr. Barrett and Brown, Ms. Locken, Mr. Maberry, and Dr. Bobula: Department of Family Medicine, University of Wisconsin—Madison, 777 South Mills, Madison, WI 53715.

    • Dr. D'Alessio: Population Health Services, 610 Walnut Street, University of Wisconsin—Madison, Madison, WI 53726.

    • Author Contributions: Conception and design: B.P. Barrett, R.L. Brown, J.A. Bobula, D. D'Alessio.

    • Analysis and interpretation of the data: B.P. Barrett, R.L. Brown.

    • Drafting of the article: B.P. Barrett.

    • Critical revision of the article for important intellectual content: B.P. Barrett, R.L. Brown, J.A. Bobula, D. D'Alessio.

    • Final approval of the article: B.P. Barrett.

    • Statistical expertise: R.L. Brown.

    • Obtaining of funding: B.P. Barrett, R. Maberry.

    • Administrative, technical, or logistic support: K. Locken, R. Maberry, J.A. Bobula.

    • Collection and assembly of data: K. Locken, R. Maberry.

    Summary for Patients

    • Summaries for Patients:Treatment of Colds with a Capsule Form of the Herb Echinacea Ann Intern Med December 17, 2002 137:I-18
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    1. Ann Intern Med December 17, 2002 vol. 137 no. 12 939-946
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