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Echinacea (Echinacea angustifolia DC, Echinacea pallida, Echinacea purpurea)
Background
Echinacea species are perennials that belong to the Aster family and originate in eastern North America. Traditionally used for a range of infections and malignancies, the roots and herb (above ground parts) of echinacea species have attracted recent scientific interest due to purported "immune stimulant" properties. Oral preparations are popular in Europe and the United States for prevention and treatment of upper respiratory tract infections (URI), and Echinacea purpurea herb is believed to be the most potent echinacea species for this indication. In the United States, sales of echinacea are believed to represent approximately 10% of the dietary supplement market.
For URI treatment, numerous human trials have found echinacea to reduce duration and severity, particularly when initiated at the earliest onset of symptoms. However, the majority of trials, largely conducted in Europe, have been small or of weak design. Negative results exist of a U.S. trial in adults, which used a whole-plant echinacea preparation containing both Echinacea purpurea and Echinacea angustifolia . Another clinical trial reported in July 2005 also did not demonstrate any clinical benefit. However, a 2006 meta-analysis investigating the efficacy of echinacea found that the likelihood of experiencing a clinical cold was 55% higher with placebo than with Echinacea (based on three trials). The sum of the current evidence is conflicting and further well-designed studies are needed before a definitive conclusion can be drawn. Lack of benefit in children ages 2-11 has also been reported.
For URI prevention (prophylaxis), daily echinacea has not been shown effective in human trials.
Preliminary studies of echinacea taken by mouth for genital herpes and radiation-associated toxicity remain inconclusive. Topical Echinacea purpurea juice has been suggested for skin and oral wound healing, and oral/injectable echinacea for vaginal Candida albicans infections, but evidence is lacking in these areas.
The German Commission E discourages the use of echinacea in patients with autoimmune diseases, but this warning is based on theoretical considerations rather than human data.
In children, echinacea cannot be recommended due to reports of rash and apparent lack of benefits in the available literature.
NS_patient-echinacea
Portions of this document last updated:Sept. 1, 2009
THE NATURAL STANDARD RESEARCH COLLABORATION
(www.naturalstandard.com)
