Echinacea : Scientific and Traditional Uses

by MedlinePlus

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 U.S. 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 methodologically flawed. 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. The sum of the evidence cannot support echinacea as a treatment for the common cold. Further research is 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 oral echinacea 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.

Synonyms

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

Evidence

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.

Uses based on scientific evidence

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. The sum of the evidence does not strongly support echinacea as a treatment for the common cold at this time.Initial research in children suggests that echinacea may not be helpful 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).

Prevention of upper respiratory tract infections (adults and children)

Preliminary studies suggest that echinacea is not helpful for preventing the common cold in adults. 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.

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.

Cancer

There is no clear human evidence of the effects of echinacea on any type of cancer.

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.

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.

Genital herpes

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

Uses based on tradition or theory

The below uses are based on tradition or scientific theories. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider.

Abscesses, acne, attention deficit hyperactivity disorder (ADHD), bacterial infections, bee stings, boils, burn wounds, cancer, cold sores, diphtheria, dizziness, eczema, gingivitis, hemorrhoids, HIV/AIDS, malaria, menopause, migraine headache, nasal congestion/runny nose, pain, psoriasis, rheumatism, skin ulcers, snake bites, stomach upset, syphilis, tonsillitis, typhoid, urinary tract infections, whooping cough (pertussis), yeast infections.

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