, commonly called Purple Coneflower
, is a genus of nine species of herbaceous
plants in the family Asteraceae
. All are strictly native to eastern and central North America
. The plants have large, showy heads of composite flowers, blooming from early to late summer. Some species are used in herbal medicines
The genus name is from the Greek echino, meaning "spiny," due to the spiny central disk. They are herbaceous, drought-tolerant perennial plants growing to 1 or 2 m in height. The leaves are lanceolate to elliptic, 10 – 20 cm long and 1.5 – 10 cm broad. Like all asteraceae, the flowers are a composite inflorescence, with purple (rarely yellow or white) florets arranged in a prominent, somewhat cone-shaped head — "cone-shaped" because the petals of the outer ray florets tend to point downward (are reflexed) once the flower head opens, thus forming a cone.
The species of Echinacea are
A controlled double-blind study
from the University of Virginia School of Medicine and documented in the New England Journal of Medicine stated that echinacea extracts had "no clinically significant effects" on rates of infection or duration or intensity of symptoms. The effects held when the herb was taken immediately following infectious viral exposure and when taken as a prophylaxis
starting a week prior to exposure.
An earlier University of Maryland review based on 13 European studies concluded that echinacea, when taken at first sign of a cold, reduced cold symptoms or shortened their duration. The review also found that three of four published studies concluded that taking echinacea to prevent a cold was ineffective.
As with any herbal preparation, individual doses may vary significantly in active chemical composition. In addition to poor process control which may affect inter- and intra-batch homogeneity, species, plant part, extraction method, and contamination or adulteration with other products all lead to variability between products.
The European Medicines Agency (EMEA) assessed the body of evidence and approved the use of expressed juice and dried expressed juice from fresh flowering aerial parts of Echinacea purpurea for the short-term prevention and treatment of the common cold. According to their recommendations,
It should not be used for more than 10 days. The use in children below 1 year of age is contraindicated, because of theoretically possible undesirable effect on immature immune system. The use in children between 1 and 12 years of age is not recommended, because efficacy has not been sufficiently documented although specific risks are not documented. In the absence of sufficient data, the use in pregnancy and lactation is not recommended.
Assessment report is also published.
Popular belief and traditional use
Echinacea is popularly believed to be an immunostimulator
, stimulating the body's non-specific immune system
and warding off infections
. A common reference source for believers is a 2007 meta-analysis
in The Lancet Infectious Diseases; however, this study fails to indicate important confounding factors that could drive the reported conclusion. The studies pooled in the meta-analysis used different types of echinacea, different parts of the plant, and various dosages. This review cannot inform recommendations on the efficacy of any particular type of echinacea, dosage, or treatment regimen. The safety of echinacea under long-term use is also unknown.
rhizome was used by North American Plains Indians
, perhaps more than most other plants, for various herbal remedies. Echinacea was one of the basic antimicrobial herbs of eclectic medicine
from the mid 19th century through the early 20th century, and its use was documented for snakebite, anthrax,and for relief of pain . In the 1930s echinacea became popular in both Europe and America as an herbal medicine.
Like most crude drugs from plant or animal origin, the constituent base for echinacea is complex, consisting of a wide variety of chemicals of variable effect and potency. Some chemicals may be directly antimicrobial, while others may work at stimulating or modulating different parts of the immune system. All species have chemical compounds called phenols
, which are common to many other plants. Both the phenol compounds cichoric and caftaric are present in E. purpurea
, other phenols include echinacoside, which is found in greater levels within E. angustifolia
and E. pallida
roots than in other species. When making herbal remedies, these phenols can serve as markers for the quantity of raw echinacea in the product. Other chemical constituents that may be important in echinacea health effects include alkylamides and polysaccharides
Root or whole plant
As with any plant, the chemical makeup of echinacea is not consistent throughout the organism. In particular, the root has been promoted as containing a more efficacious mixture of active chemicals. A 2003 study in the Journal of the American Medical Association (Taylor et al.
2003) found that when echinacea products made from the entire plant were taken after the second cold symptom appeared they provided no measurable beneficial effect for children in treating the severity or duration of symptoms caused by the common cold virus. The study has been criticized for using whole-plant extracts instead of root extracts, and the dosages studied were lower than those recommended by herbalists. A 2005 study in the New England Journal of Medicine (Turner, 2005) focused on several root extracts, but still found no statistically significant effects on duration, intensity, or prevention of symptoms.
Frequency of administration
Proponents of echinacea assert that it is not a "one-dose" treatment, and that in order to work effectively, a dose should be taken at the very first sign of a cold symptom. Subsequent doses are called for every two to four hours after the first dose, including during the overnight sleeping period, until the cold symptoms have disappeared.
The several species of echinacea differ in their precise chemical constitution, and may provide variable dosages of any active ingredients.
Side effects and contraindications
Reported adverse effects of echinacea include nausea
, and hepatotoxicity
. These tend to be infrequent, mild, and transient. Echinacea should not be taken by persons with progressive systemic and auto-immune disorders, connective tissue disorders, or related diseases. It should not be used with immunosuppressants
or hepatotoxic drugs
, and has the potential to interfere with anesthesia.
In one investigation by an independent consumer testing laboratory, five of eleven selected retail echinacea products failed quality testing. Four of the failing products contained measured levels of phenols believed to be related to potency below the levels stated on the labels. One failing product was contaminated with lead.
Some species of echinacea, notably E. purpurea
, E. angustifolia
, and E. pallida
, are grown as ornamental plants
in gardens. They tolerate a wide variety of conditions, maintain attractive foliage throughout the season, and multiply rapidly. Appropriate species are used in prairie