Does Echinacea Really Work?

• Controversial Study Conclusion
• Effects Depends on Echinacea Species

There have been a number of studies on the effects of echinacea on various conditions. A frequent area of research is on whether or not echinacea can prevent or reduce the symptoms of the common cold. Results from clinical studies, however, have yielded conflicting results. Why does that happen, and what does it mean in terms of figuring out if echinacea is effective?⁽⁴⁹⁾

Main Source of Statements that Echinacea is Ineffective

Results of one of the largest randomized, controlled clinical trials on echinacea, published in the New England Journal of Medicine in 2005, are often cited as the final word on echinacea's effectiveness in treating viral infections. The results of this study showed that echinacea did not offer any preventive or therapeutic benefit with the common cold.^(8, 25)

The study involved 399 participants. All were exposed to a particular variant of the common cold virus and sequestered for five days. During that time, subjects were randomly treated with either a placebo or with one of three different extracts from E. angustifolia roots.⁽⁸⁾

Why Is That Conclusion Controversial?

Before relegating echinacea to only a pretty addition to your garden, you may want to take another look. The researchers involved in the 2005 trial themselves point out the difficulties in researching the possible health benefits of any plant. These obstacles include:^{(8, 25, 99, 100, 112)}

• Species used.
• Doses given.
• Standardization of active compounds.

All of these can explain the variations in results from one experiment to another.^(8, 49)

There were other controversial aspects of the NEJM study as well:

Echinacea Species Used in Trial Least Studied

Two highly respected experts point out that the NEJM trial used Echinacea angustifolia. This echinacea species is relatively unstudied, and it's odd that it was chosen over the echinacea species (E. pallida) found by the German Commission E to be supported by scientific data. Moreover, the dosage used in the trial wasn't even close to the recommended dosage of E. pallida.⁽¹¹³⁾

Bottom Line — Effects Depends on Echinacea Species

This trial is a good indication that extracts of E. angustifolia roots may not work for colds at the dosage used. However, it certainly is not conclusive evidence on the efficacy of echinacea as a whole.^(8, 25)

Comprehensive expert reviews of multiple clinical trials have found echinacea effective in preventing and treating the common cold and flu. In fact, a clinical trial using E. angustifolia and E. purpurea with standardized active compounds showed the echinacea combination prevented upper respiratory tract infections or reduced symptoms in adults.^{(49, 100, 113)}