Herbs & Supplements:
Echinacea
Echinacea purpurea, E. angustifolia, E. pallida
Principal Proposed Uses
•
Colds and Flus (Shortening the Duration, Reducing Symptoms)
Other Proposed Uses
•
Stimulating Immunity, "Aborting" a Cold That Has Just Started, Preventing Colds, Helping the Body Fight Off Other Infections
The decorative plant Echinacea purpurea, or purple coneflower, has been one of the most popular herbal medications in both the United States and Europe for over a century.
Native Americans used the related species Echinacea angustifolia for a wide variety of problems, including respiratory infections and snakebite. Herbal physicians among the European colonists quickly added the herb to their repertoire. Echinacea became tremendously popular toward the end of the nineteenth century, when a businessman named H. C. F. Meyer promoted an herbal concoction containing E. angustifolia. The garish, exaggerated, and poorly written nature of his labeling helped define the characteristics of a "snake oil" remedy.
However, serious manufacturers developed an interest in echinacea as well. By 1920, the respected Lloyd Brothers Pharmaceutical Company of Cincinnati, Ohio, counted echinacea as its largest-selling product. In Europe, physicians took up the American interest in E. angustifolia with enthusiasm. Demand soon outstripped the supply coming from America, and, in an attempt to rapidly plant echinacea locally, the German firm Madeus and Company mistakenly purchased a quantity of Echinacea purpurea seeds. This historical accident is the reason why most echinacea today belongs to the purpurea species instead of angustifolia. Another family member, Echinacea pallida, is also used.
Echinacea was the number one cold and flu remedy in the United States until it was displaced by sulfa antibiotics. Ironically, antibiotics are not effective for colds, while echinacea appears to offer some real help. Echinacea remains the primary remedy for minor respiratory infections in Germany, where over 1.3 million prescriptions are issued each year.
What Is Echinacea Used for Today?
In Europe, and increasingly in the U.S. as well, echinacea products are widely used to treat colds and flus.
The best scientific evidence about echinacea concerns its ability to help you recover from colds and minor flus more quickly. The old saying goes that a "cold lasts 7 days, but if you treat it, it will be over in a week." However, good evidence tells us that echinacea can actually help you get over colds much faster. It also appears to significantly reduce symptoms while you are sick. Echinacea may also be able to "abort" a cold, if taken at the first sign of symptoms.
However, taking echinacea regularly throughout cold season is probably not a great idea. Evidence suggests that it does not work for this purpose.
We don't know exactly how echinacea helps colds and flus, but it is thought to stimulate the immune system in the short term. Test tube and animal studies have found that various constituents of echinacea can increase antibody production, raise white blood cell counts, and stimulate the activity of key white blood cells.1–6 However, in a study that involved daily use of echinacea for 6 months, no changes in immune measurements were seen.7 In other words, echinacea appears to stimulate the immune system temporarily, rather than strengthen it.
Echinacea is also sometimes tried for other infectious illnesses, but there is no direct evidence as yet that it works. One study did not find it effective for preventing herpes flare-ups.8
What Is the Scientific Evidence for Echinacea?
Reducing the Symptoms and Duration of Colds
Double-blind, placebo-controlled studies enrolling a total of more than 800 individuals have found that various forms and species of echinacea can reduce cold symptoms, and help you get over a cold faster.9–16 The best evidence regards products made from the above-ground portions of E. purpurea.
For example, in one double-blind placebo-controlled trial, 80 individuals with early cold symptoms were given either E. purpurea extract or placebo.17 The results showed that individuals who were given echinacea recovered significantly more quickly: just 6 days in the echinacea group versus 9 days in the placebo group.
Another double-blind placebo-controlled trial looked at reduction in the severity of cold symptoms.18 The results in 246 participants showed that treatment with E. purpurea significantly improved cold symptoms such as runny nose, sore throat, sneezing, and fatigue.
"Aborting" a Cold
A double-blind study suggests that echinacea can not only make colds shorter and less severe, it might also be able to stop a cold that is just starting.19 In this study, 120 people were given E. purpurea or a placebo as soon as they started showing signs of getting a cold.
Participants took either echinacea or placebo at a dosage of 20 drops every 2 hours for 1 day, then 20 drops 3 times a day for a total of up to 10 days of treatment. The results were promising. Fewer people in the echinacea group felt that their initial symptoms actually developed into "real" colds (40% of those taking echinacea versus 60% taking the placebo actually became ill). Also, among those who did come down with "real" colds, improvement in the symptoms started sooner in the echinacea group (4 days instead of 8 days). Both of these results were statistically significant.
Preventing Colds
Several studies have attempted to discover whether the daily use of echinacea can prevent colds from even starting, but the results have not been promising.
In one double-blind placebo-controlled trial, 302 healthy volunteers were given an alcohol tincture containing either E. purpurea root, E. angustifolia root, or placebo for 12 weeks.20 The results showed that E. purpurea was associated with perhaps a 20% decrease in the number of people who got sick, and E. angustifolia with a 10% decrease. However, the difference was not statistically significant. This means that the benefit, if any, was so small that it could have been due to chance alone.
Another double-blind placebo-controlled study enrolled 109 individuals with a history of four or more colds during the previous year, and gave them either E. purpurea juice or placebo for a period of 8 weeks.21 No benefits were seen in the frequency, duration, or severity of colds. (Note: this paper is actually a more detailed look at a 1992 study widely misreported as providing evidence of benefit.)22
Similar results were seen in three other studies as well, enrolling a total of over 300 individuals.23,24 Another study often cited as evidence that echinacea can prevent colds actually found no benefit in the 609 participants taken as a whole.25 Only by looking at subgroups of participants (a statistically questionable procedure) could researchers find any evidence of benefit, and it was still slight.
Dosage
Echinacea is usually taken at the first sign of a cold and continued for 7 to 14 days. Longer-term use of echinacea is not recommended.
The typical dosage of echinacea powdered extract is 300 mg 3 times a day. Alcohol tincture (1:5) is usually taken at a dosage of 3 to 4 ml 3 times daily, echinacea juice at a dosage of 2 to 3 ml 3 times daily, and whole dried root at 1 to 2 g 3 times daily. The best evidence supports the use of products made from the above-ground portions of E. purpurea, although other forms of echinacea may be effective as well. There is no broad agreement on what ingredients should be standardized in echinacea tinctures and solid extracts.
Many herbalists feel that liquid forms of echinacea are more effective than tablets or capsules, because they feel part of echinacea's benefit is due to activation of the tonsils through direct contact.26 However, there is no real evidence to support this contention.
Finally, goldenseal is frequently combined with echinacea in cold preparations. However, there is not a shred of evidence that oral goldenseal stimulates immunity, nor did traditional herbalists use it for this purpose.27
Safety Issues
Echinacea appears to be generally safe. Even when taken in very high doses, it has not been found to cause any toxic effects.28,29 Reported side effects are also uncommon and usually limited to minor gastrointestinal symptoms, increased urination, and mild allergic reactions.30 However, severe allergic reactions have occurred occasionally, some of them life threatening.31In Australia, one survey found that 20% of allergy-prone individuals were allergic to echinacea.
Other concerns relate to echinacea’s apparent immune-stimulating properties. Immunity is a two-edged sword that the body keeps under careful control; excessively strong immune reactions can be dangerous. Based on this concern, echinacea should be used only with caution (if at all) by individuals with autoimmune disorders, such as multiple sclerosis, lupus, and rheumatoid arthritis.
Furthermore, a recent case report strongly suggests that use of echinacea can trigger episodes of erythema nodosum (EN). 36 EN is an inflammatory condition that involves tender nodules under the skin. These nodules often arise after cold-like symptoms. In this report, a 41-year-old man took echinacea on four separate occasions when he thought he was developing a cold, and each time he developed EN instead. When he stopped using echinacea for this purpose, he remained free of EN outbreaks for a full year of follow-up. The cause of EN is not known, but it involves increased activity of certain immune cells; echinacea has been observed to cause similar effects in the same immune cells, suggesting that the relationship is not coincidental.
One study raised questions about possible anti-fertility effects of echinacea.32 When high concentrations of echinacea were placed in a test tube with hamster sperm and ova, the sperm were less able to penetrate the ova. However, since we have no idea whether this much echinacea can actually come in contact with sperm and ova when they are in the body rather than a test tube, these results may not be meaningful in real life.
One study found evidence that use of echinacea during pregnancy does not increase risk of birth defects.33 Furthermore, studies dating back to the 1950s suggest that echinacea is safe in children.34 Nonetheless, the safety of echinacea in young children or pregnant or nursing women cannot be regarded as established. In addition, safety in those with severe liver or kidney disease has also not been established.
One study suggests that echinacea might interact with various medications by affecting their metabolism in the liver, but the extent of this effect has not been fully determined.35
View References
Last reviewed March 2002 by Medical Review Board
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