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Category

Herbs & Supplements

Synonyms

American coneflower, black Sampson, black Susan, cock-up-hat, combflower, Echinacin®, Echinaforce®, Echinaguard®, hedgehog, igelkopf, Indian head, Kansas snake root, kegelblume, narrow-leaved purple coneflower, purple coneflower, red sunflower, rudbeckia, scurvy root, snakeroot, solhat, sun hat.

Background

Echinacea species are perennials which belong to the Aster family and which 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 U.S., 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 E. purpurea and E. angustifolia. Another clinical trial reported in July 2005 did not demonstrate any clinical benefit either. 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 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 E. 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 use of echinacea in patients with autoimmune diseases, but this warning is based on theoretical considerations rather than human data.

Evidence

DISCLAIMER: These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Cancer: There is no clear human evidence of the effects of echinacea on any type of cancer.
Grade: C

Immune system stimulation: Echinacea has been studied alone and in combination preparations for immune system stimulation (including in patients receiving cancer chemotherapy). It remains unclear if there are clinically significant benefits. Additional studies are needed in this area before conclusions can be drawn regarding safety or effectiveness.
Grade: C

Low white blood cell counts after X-ray treatment: Studies have reported mixed results, and it is not clear whether echinacea has benefits for this use.
Grade: C

Prevention of upper respiratory tract infections (adults and children): Preliminary studies suggest that echinacea is not helpful for preventing the common cold in adults. A recent meta-analysis suggested that standardized extracts of echinacea were effective in the prevention of symptoms of the common cold after clinical inoculation, compared with placebo. In children, a combination of echinacea, propolis, and vitamin C has been reported to reduce the number and duration of cold episodes. However, prevention research overall has not been well designed, and additional trials are needed before a clear conclusion can be drawn.
Grade: C

Treatment of upper respiratory tract infections (adults): Although multiple low quality studies have previously suggested that taking echinacea by mouth by adults when cold symptoms begin may reduce the length and severity of symptoms, a clinical trial reported in July 2005 did not demonstrate any clinical benefit. Recent meta-analyses are conflicting; one suggested that standardized extracts of echinacea were effective in the prevention of symptoms of the common cold after clinical inoculation, compared with placebo, whereas the other reported no such benefit. Further research is needed.
Grade: C

Genital herpes: Initial human studies suggest that echinacea is not helpful in the treatment of genital herpes.
Grade: D

Treatment of upper respiratory tract infections (children): Initial research suggests that echinacea may not be helpful in children for alleviation of cold symptoms, possibly because parents are not able to recognize the onset of common cold symptoms soon enough to begin treatment, or because the dose of echinacea for use in children is not clear. There are fundamental differences in causes of upper respiratory tract infection symptoms in children versus adults (bacterial versus viral causes; different viruses; different sites of infection; etc). Until additional research is available, echinacea cannot be considered effective in children for this use. Furthermore, development of rash has been associated with echinacea use, and therefore the risks may outweigh the potential benefits in this population.
Grade: D