Echinacea And Colds
Chester J. Zelasko, Ph.D. | August 26, 2005

“Echinacea doesn’t work for colds.” That’s what the health and medical headlines read several weeks ago. The battle is on between those who say echinacea is effective for the reduction of the severity and duration of colds and those who say it doesn’t work. First, let’s review the study and the results and then examine the details of how the study was conducted.

The study
The purpose of the study was to test the efficacy of a tincture of echinacea on preventing colds and reducing the symptoms and duration of colds. The researchers tested a large group of students to see if they were susceptible to a specific strain of cold--rhinovirus 39. Those who were not susceptible because they had been exposed to that strain of cold were excluded from the study. The researchers prepared the echinacea tincture from the root of Echinacea angustifolia (commonly known as narrow-leafed purple coneflower) and administered it to half the subjects seven days before the exposure to the cold virus and to all subjects for five days after exposure to the cold virus. Subjects were sequestered in hotel rooms for the duration of the study to prevent complicating exposures to other viruses.

There were no significant differences between those taking a placebo versus those taking the tincture, or liquid echinacea solution, before and after exposure to the cold virus. The same number of subjects got colds and had the same number of symptoms and other measures of immune responses to colds. Bottom line from the researchers: echinacea is ineffective.

The problems
There’s no question that this study was well designed. The researchers tried to eliminate confounding factors; they gave the subjects the exact same type of cold and the exact same tincture of echinacea. But in spite of their best efforts, there were some major flaws in the study’s execution.

Only one type of echinacea: The researchers used only a single form of echinacea and only a single part of the plant--the root. Most herbal blends use multiple forms of echinacea; they use the root and other parts of the plant as well.

Quantity of echinacea lower than recommended: The subjects were given the equivalent of 900 mg of echinacea root in the tincture over the course of the day; the researchers gave no explanation why that amount was used. Typically, the amount of echinacea recommended at the onset of a cold is two to six times the amount used in this study.

Subject loss higher than acceptable: Of all the things not addressed by the researchers, this one is probably the most disturbing from a statistical point of view. Eliminating subjects who have been exposed to the specific form of the cold is understandable and reasonable. But the researchers did not address why half the remaining subjects chose not to participate in the study nor why another 10% dropped out during the study. Subject loss that severe has dramatic effects on the outcome of any study. The simplest explanation is that the subjects didn’t want to get a cold or didn’t want to be sequestered in a hotel room for days. But the researchers didn’t address this issue. We’ll never know.

Light-sensitive form of echinacea: Research has demonstrated that echinacea in liquid form has some components that are activated by exposure to light (3). While the researchers did a good job of examining what phytonutrients were in the echinacea extract, if the echinacea were left in glass jars exposed to the light for as little as five minutes, the active ingredients could have been activated and rendered ineffective by the time of administration.

The bottom line
The only reasonable conclusion is that this was a well-designed study that was poorly executed. These are experienced researchers who approached this as one would approach a pharmaceutical study. The problem is that they didn’t appear to utilize anyone experienced in the typical use of this herb--and that affected critical elements of the study.

In an editorial about the study in the same journal issue, Dr. Wallace Sampson recommended that funding for alternative medicines be stopped because they are not rooted in science and there is no evidence that they work. In one aspect, Dr. Sampson may be correct: perhaps the U.S. government should quit funding research on alternative medicine, but not because alternative medicine is ineffective. If the National Center for Complementary and Alternative Medicine is going to continue to fund studies by scientists inexperienced in the basics of using herbal extracts, then the money would best be spent on other research, because doing research this poorly is a waste of taxpayer money.

Should you use echinacea or not? If you’ve found that it has been effective for colds, flu, or other types of infections, there’s no reason to stop based on this research. We at Better Life continue to use standardized extracts of echinacea for one reason: in our experience, it works.


  1. Turner, RB, et al. An Evaluation of Echinacea angustifolia in Experimental Rhinovirus Infections. N Engl J Med 2005;353:341-8.
  2. Sampson, W. Studying Herbal Remedies. N Engl J Med; 2005;353:337-339.
  3. Binns SE, et al. Light-mediated antifungal activity of Echinacea extracts. Planta Med. 2000; 66(3):241-4.
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