Clinical use of echinacea
- Robert B Saper, MD, MPH
Robert B Saper, MD, MPH
- Associate Professor of Family Medicine
- Boston University School of Medicine
Echinacea species are commonly referred to as coneflowers, a group of native American wildflowers from the daisy family (Asteraceae/Compositae) (picture 1) . Echinacea is indigenous to North America and was used by Native Americans in the Great Plains. Samples of echinacea have been found in archeological digs from the 1600s, thought to be the location of Lakota Sioux Indian village sites . Native Americans were noted to use echinacea both topically and systemically for ailments such as burns, snakebites, pain, cough, and sore throat .
Various echinacea species including Echinacea purpurea, E. angustifolia, and E. pallida have been touted as "immune stimulants" by a number of investigators . Medicinal preparations of root and above-ground parts of echinacea species have been the subject of in vitro, animal, and human studies to evaluate their possible mechanism(s), safety, and efficacy.
At present, echinacea is mainly used for treating and preventing uncomplicated upper respiratory tract infections such as the common cold . Sales of echinacea in the United States in 2008 were estimated to be $15.1 million, a 4.5 percent increase from 2007 . The National Health Interview Survey found that echinacea was the third most common natural product used by adults in the US in 2007, used by 4.8 million adults . Echinacea was the most commonly used herbal product by children in the US . In Germany, more than 2 million physicians' prescriptions for echinacea are filled each year . (See "Overview of herbal medicine and dietary supplements" and "The common cold in adults: Treatment and prevention".)
MECHANISM OF ACTION
Echinacea products contain a variety of bioactive ingredients including echinacosides, caffeic acids, alkylamides, polysaccharides, and glycoproteins . Though several echinacea products are standardized to the amount of echinacosides, there is no general consensus on the active component(s) of echinacea responsible for its purported medicinal properties.
In vitro, echinacea causes macrophage activation and the release of tumor necrosis factor, interleukin 1, interleukin 6, and interferon [9-11]. Echinacea has been noted to have antiviral activity against influenza , herpes , and poliovirus. Phenolic compounds present in echinacea demonstrate antioxidant activity . It has also been reported to have antiinflammatory activity through inhibition of lipoxygenase and cyclooxygenase  and is able to stimulate the anterior pituitary-adrenal cortex.
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