Because the active component of the plant has not been fully identified, commercial echinacea products are not typically standardized to any particular component.

Echinacea Mechanism of Action
Echinacea plant extract is widely used for the prevention and treatment of upper respiratory tract infections. Echinacea has been the subject of hundreds of studies, however, the active components in the herb, their optimal dosages and their in vivo effects are still not fully identified. The actions of echinacea are thought to be due to a number of polysaccharides called fructofuranosides, such as heteroxylan and arabinogalactan, and also to a group of lower molecular-weight polysaccharides, including alkylamides and echinacosides.
   Many of the compounds in echinacea stimulate various aspects of the immune system including macrophage and lymphocyte function. Natural killer cell activity is increased and there may be an increase in interferon production and phagocytosis.

Does echinacea prevent cold?
Echinacea, which is derived from the coneflower, has long been touted as a way to bolster immunity and prevent or ease the common cold. But studies have come to conflicting conclusions as to whether the herb is truly effective.
       
Echinacea side effects
As with most herbal products, small amounts are usually quite safe. There have been rare cases of allergic reactions to echinacea. It may be best for those with autoimmune diseases to not use echinacea (see study below).

Echinacea Summary
Echinacea herb has an influence on the immune system. The scientific evidence regarding echinacea's effectiveness in limiting common cold severity and duration is inconsistent. The research literature on echinacea is difficult to evaluate because of the differences in products used in various studies.
    In a study with children, echinacea purpurea was not effective in treating upper respiratory infection symptoms in patients 2 to 11 years old, and its use was associated with an increased risk of rash.
   A June, 2004 study found taking 300 milligrams per day of Echinacea at the first sign of a cold appears to do little to reduce symptoms or speed recovery.
   At this point the use of echinacea to treat or prevent the common cold has its proponents and critics. We believe zinc lozenges and vitamin C are more effective taken early in the onset of a cold has potential than echinacea, but echinacea may play a positive role in some people.

Echinacea study
Activation of autoimmunity following use of immunostimulatory herbal supplements.
Lee AN, Werth VP.
Section of Dermatology, University of Chicago, IL, USA.
Arch Dermatol. 2004 Jun;140(6):723-7.
Evidence for the scientific basis of purported therapeutic effects and adverse effects of herbal supplements continues to grow. Many herbal supplements are touted for their immunostimulatory properties, and both in vitro and in vivo experiments have supported this claim. Although this explains their beneficial effects in preventing or curtailing disease, to our knowledge, no immunostimulatory herbal supplements have been reported to exacerbate disorders of immune system overactivity. We describe 3 patients whose autoimmune disease onset and/or flares correlated with ingestion of herbal supplements with proven immunostimulatory effects. Echinacea and the alga Spirulina platensis are implicated in 2 patients' flares of pemphigus vulgaris, and a supplement containing the algae Spirulina platensis and Aphanizomenon flos-aquae was ingested by a third patient days before both onset and a severe flare of dermatomyositis. The third patient showed heterozygosity for a tumor necrosis factor alpha (TNF-alpha) promoter polymorphism (-308A), leading to increased production of TNF-alpha, which may have predisposed her to developing dermatomyositis. Immunostimulatory herbal supplements may exacerbate preexisting autoimmune disease or precipitate autoimmune disease in persons genetically predisposed to such disorders. Increased production of TNF-alpha may play a role, although more research is needed to clarify the mechanisms of such phenomena.

Stocking your medicine cabinet with Echinacea may be a waste of time, as a new study shows the herbal medicine does not help prevent colds. After exposing 48 healthy adults to a virus that causes the common cold, U.S. investigators found that people who took Echinacea were no less likely to develop colds than people who took an inactive placebo pill. Consequently, people may be better off leaving Echinacea off of their grocery list, study author Dr. Steven Sperber of Hackensack University Medical Center in New Jersey told Reuters Health. "Echinacea did not prevent infection with the cold virus," he said. The research was funded by the German company Madaus Aktiengesellschaft, which sells the Echinacea product used in the current study. In the U.S. alone, consumers spend more than $300 million each year on Echinacea products, for the purpose of preventing and treating colds. However, recent research has also cast doubt on whether the herbal preparation can treat colds. A study published last year found that children who took Echinacea as soon as they developed a cold showed no difference in the severity or duration of cold symptoms than children who took a placebo pill.

Efficacy of Echinacea purpurea in patients with a common cold. A placebo-controlled, randomised, double-blind clinical trial.
Arzneimittelforschung 2001;51(7):563-8. Company Medical Service, Madaus AG, Cologne, Germany.
Common colds are one of the most frequent acute illnesses with major economical impact. Echinaceae purpureae herba (Echinacin, EC31J0) has shown promising results in the relief of common cold symptoms and the time taken to improvement compared to placebo. This study was aimed to confirm these findings by performing a randomised, double-blind, placebo-controlled clinical trial. A total of 80 adult male or female patients with first signs of a cold were recruited. The number of days of illness with a complete picture of the common cold (defined by the modified Jackson score of at least 5 points and experience of rhinorrhea and/or a subjective sensation of having a cold) was the primary end-point. In the verum group the median time of illness was 6.0 days compared to 9.0 days in the placebo group, assigning zero time for patients without a complete picture (one-sided p = 0.0112). EC31J0 was well tolerated and clinically effective in alleviating symptoms more rapidly than placebo in patients with a common cold.

2002 study
Echinacea at a dose of 800 mg twice daily for six months was not effective in reducing the frequency of recurrent genital herpes.

Echinacea questions
Q. If one takes echinacea daily over a period of a couple of months could this possibly result in higher blood pressure -- even when one is taking blood pressure medicine? Can echinacea herb be combined with AHCC supplement?
   A. We are not aware of any research that indicates echinacea is involved with blood pressure. AHCC and echinacea work in different ways, it is difficult to predict their effect when combined.

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