While no drug interactions have been reported with Echinacea, caution is been recommended in patients taking prescription medications non to be metabolized via the cytochrome P450 enzyme system: echinacea extracts have been found, in vitro, to effect the activity of isozyme 3A4. 8
Information on the relationship between substances and disease is provided for general information, in order to convey a balanced review of the scientific literature. In many cases the relationship between a substance and a disease is tentative and additional research is needed to confirm such a relationship.
Common Names: American coneflower, black Sampson, black Susan, comb flower, headgehog, Kansas snakeroot, Missouri snakeroot, (E.angudtifolia): narrow-leaved purple coneflower, (E. purpurea): common purple coneflower, (E. pallida): pale purple coneflower. scurvy root.
Echinacea consists of either fresh above ground parts, harvested at flowering time, or dried roots.
Three species are found in medicinal plant preparations:
E, angustifolia is native to the American Midwest. It is a perennial herb and grows up to 60 cm in height. The flower has thick narrow leaves and bears a single purple flower emanating from a cone-shaped center.
E. pallida grows up to about 120 cm in height; it has long ray flowers and can be found in open woods and rocky prairies. It is found from northeast Texas to Indiana.
E. purpurea, up to 90 cm in height is the most common of the nine species that grow in the Midwest. More than 200 pharmacologic and clinical studies have involved E. purpurea preparations. 1
Note: A recent taxonomic revision of the genus Echinacea designates the former E. angustifolia and E. pallida as varieties of E. pallida, namely, E. pallida var. angustifolia and E. pallida var. pallida [Binns SE, Baum BR, Arnason JT. A taxonomic revision of Echinacea (Asteraceae: Heliantheae Systematic Botany 2002]
Echinacea has been shown in human and /or animal experiments to have:
Nonspecific cellular immune or immunostimulatory effects.
Bactericidal and wound healing actions.
In vitro, alcoholic root extracts show a 23% increase in phagocytic elements when tested in granulocyte smears.
About 300 echinacea pharmaceutical products are available in Europe. 2 Recommendations for oral dosages are difficult on account of the wide variety of preparations and doses used in the published clinical trials.
E. purpurea herb
Internal: 6-9 ml expressed juice, equivalent preparations.
External: Semi-solid preparations containing at least 15% expressed juice for a maximum of 8 weeks. E. purpurea root
Internal: 0.9 g cut root several times daily, equivalent preparations
E. pallidaherb and root
900 mg of native dried extract (50% ethanol) for a maximum of 8 weeks. E. augustifolia herb and extract
Internal: 1 g cut root several times daily E. augustifolia root
0.9 g cut root several times daily for teas and other galenical preparations
*Upper limit unknown. Active Ingredients: The main active constituents of echinacea are believed to be the alkylamides (alkamides), ketoalkenes/ketoalkynes, glycoproteins, caffeic acid derivatives (e.g. cichoric acid and caftaric acid ) and polysaccharides. 4, 5
Side effects, generally rare and mild, include: rashes itching, occasional swelling of the face, breathing difficulties and dizziness.
Contraindications: Because no clinical studies include infants or pregnant women, extra caution should be taken with these individuals. However, a controlled study compared 206 women who reported gestational use of echinacea to the Motherisk program at Toronto’s Sick Children’s Hospital (112 reported first trimester use) with 206 controls; there were no significan differences between groups for major or minor malformations. 6
People with environmental allergies may have an adverse reaction to echinacea. Atopic individuals should be cautioned appropriately. 7
N.B. The often noted contraindication, deriving from the German Commission E, recommending avoidance of Echinacea by patients with autoimmune disorders, AIDS, HIV infection or tuberculosis is not supported by any clinical observation.
Chochrane Review: Echinacea extracts are widely used by patients and practitioners in certain parts of Europe and the United States for preventing and treating upper respiratory tract infections. Despite the widespread use, there is considerable debate about the effectiveness of Echinacea. A detailed Cochrane review published in 2005 assessed the available evidence from randomized clinical trials investigating the effectiveness of Echinacea extracts for the prevention and the treatment of the common cold. To be included in the overview, trials must include clinical outcome measures related to occurrence, severity or duration of infections. Sixteen trials, 8 prevention trials and 8 treatment trials, with a total of 3,396 participants were reviewed. The overall results suggest that some Echinacea preparations may be better than placebo, effective in both the treatment and prevention of the common cold, and may be more effective for treatment when taken at the onset of symptoms, however, more research is needed to confirm this effect.13
In the 5 prevention trials with a placebo control, 2 found a statistically significant lower incidence of infection in the treatment group. 1415 One (Forth, 1981) used an herbal preparation containing various herbs including Echinacea angustifolia and pallida roots and was given in drops or tablets for 16 weeks. The second study (Hoheisel 1997) used a pressed juice of Echinacea purpurea given in drops for 10 days. Hoheisel and colleagues also found that the duration of illness was significantly shorter in the treatment group. The remaining trials found only trends in favor of the treatment groups.
In all 3 prevention trials with no treatment controls (Helbig 1961, Kleinschmidt 1965, Freyer 1974), the number of children with infection was significantly lower in the group receiving the Echinacea combination compared to the no treatment group. All 3 trials lasted 6 weeks and used an herbal preparation containing various herbs including Echinacea angustifolia and pallida roots administered in drops. 161718
6 of the 8 treatment trials suggest significantly positive results for the tested preparations over placebo. Preparations found to be effective included Echinacea purpurea root extract drops, Echinacea pallida root extract drops, a combination tablet containing Echinacea purpurea root, a combination tablet containing Echinacea angustifolia and pallida roots, and a combination tincture containing Echinacea angustifolia. 121920212223 In the remaining trials, one found significant results for a subgroup only (Henneicke 1997) and two found no difference after treatment (Braunig 1992 low dose, and Dorn 1989.)2425
Upper Respiratory Tract Infections: Upper respiratory infection (URI) is usually viral and is commonly associated with rhinosinusitis and pharyngitis. URI is the highest-incidence acute illness in industrialized societies.
Non of the three randomized controlled trials of echinacea-only products for the prevention of URIs found a benefit. 4
A 1998 study investigated the safety and efficacy of 2 extracts of echinacea in the prevention of URIs. The time until occurrence of the first URI was determined in 302 volunteers after taking 50 drops of ethanolic extracts from the roots of E. angustifolia, E. purpurea, or placebo 2 times a week for 12 weeks. The authors concluded that echinacea may reduce the risk of developing a URI by 10 to 20%. 9
A 1999 study looked at 9 treatment trials and 4 prevention trials on the effectiveness of orally ingested Echinacea extracts in reducing the incidence of acute URIs. The authors concluded that evidence from the published trials suggests that Echinacea may be beneficial in the early treatment of acute URIs. 10
The Common Cold: In 1999, a study looked at the efficacy and safety of echinacea pupurea preparations of up to 7 times higher concentrations than normal dosing in the treatment of the common cold. Patients were given either 6.78 mg echinacea purpurea crude extract 95% herb and 5% root, 48.27 mg of crude extract, 29.60 mg of crude root extract only, or placebo. The results revealed the 6.78 mg of the herb and the root was more effective in the treatment of the common cold than the concentrated root preparation alone. 11 Influenza Infections/Flu-like infections: A double-blind study was done to compare echinacea to placebo for strengthening the immune response in flu-like or feverish infections of the URI. Patients were given either 450 mg, 900 mg of echinacea purpurea or placebo for 10 days. The researcher found the 900 mg dose was most effective in relieving symptoms of hoarseness, coughing and decreasing the duration of the illness. The length of the illness was also reduced from 13 to 9 days compared to the placebo and the strongest benefits were seen after 8 to 10 days. 12
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