Echinacea and the Common Cold Controversy

Taking whole, unrefined echinacea root does not reduce the duration or severity of cold symptoms in adults, according to a new study in Annals of Internal Medicine (2002;137:939–46). This is the latest study to add to the debate over the effectiveness of echinacea in treating colds and flus.

In this study, 142 college students were assigned to receive 6 grams per day of a dried mixture of echinacea (E. angustifolia root, E. purpurea root, and E. purpurea whole herb) at the initial onset of cold symptoms and then 3 grams per day for up to ten days or a placebo taken in the same amounts. The severity and duration of symptoms were recorded daily. No significant difference in the severity or duration of cold symptoms was observed in those taking the echinacea compound, compared with those taking placebo.

The lack of benefit in the echinacea group would suggest that echinacea is ineffective against the common cold; however, several other studies have shown that echinacea significantly reduces the duration and severity of cold symptoms. One study showed that cold symptoms were less severe and resolved more quickly after taking 60 drops per day of an alcohol extract of E. pupurea. Another study demonstrated that 180 drops per day of E. purpurea also decreased the length and severity of colds. Other studies using different species of echinacea, such as E. angustifolia and E. pallida have shown similar results. (While studies have shown that echinacea can reduce a cold when taken at the onset of symptoms, little evidence suggests it is effective in preventing colds.)

The discrepancy between the new study and other studies is likely due to the type of preparation used by the researchers. The echinacea mixture used in the study was made from whole, unrefined roots of the two species, with the addition of the whole plant of E. purpurea. Almost all of the published studies examining echinacea and the common cold have used either an alcohol extract (also called a tincture) from the three different species or the pressed juice from E. purpurea. (Alcohol extracts are commonly used by herbalists to increase the concentration of some active constituents from the plant.) Although no single substance is known to be the active ingredient in echinacea, it is possible that tinctures contain higher amounts of certain immune-enhancing chemicals than the unrefined roots and whole plants.

Traditional herbalists typically use echinacea as a tincture. Many of the preparations available in the United States are from E. purpurea, E. angustifolia, or a combination of both. There is no evidence that one species is more effective than another. The quality of an echinacea tincture can be determined by the taste. Fresh echinacea will cause a tingling sensation on the tongue (due to the presence of compounds called isobutyl amides), which diminishes as the tincture ages. Some herbalists recommend taking 20 drops of a 1:5 alcohol extract every two hours at the onset of cold symptoms and then 20 drops, three times a day until the cold resolves.

Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.

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