A signficant amount of research has been conducted to investigate the role of echinacea in preventing and treating the common cold.
Double-blind, placebo-controlled studies enrolling a total of more than 1,000 people have found that various forms and species of echinacea can reduce the symptoms and duration of a common cold, at least in adults.14-21,115,145
For example, in one double-blind, placebo-controlled trial, 80 individuals with early cold symptoms were given either E. purpurea extract or placebo.22 The results showed that individuals who were given echinacea recovered significantly more quickly: in just 6 days among the echinacea group versus 9 days among the placebo group.
Another double-blind, placebo-controlled trial looked at reduction of the severity of cold symptoms.23 The results in 246 participants showed that treatment with E. purpurea significantly improved cold symptoms such as runny nose, sore throat, sneezing, and fatigue. Symptom reduction with E. purpurea was also seen in a double-blind, placebo-controlled study of 282 people.115
In addition, three double-blind, placebo-controlled studies enrolling a total of about 600 participants found similar benefits with a combination product containing E. purpurea and E. pallida root, along with wild indigo and white pine.106-107,140-141
While the above evidence tends to suggest that the above-ground portion of E. purpurea is active against the common cold, two studies have failed to find benefit. One of these was a double-blind, placebo-controlled study enrolling 120 adults,116 the other an even larger trial (407 participants) involving children.117 The reason for these negative outcomes is not clear. E. angustifolia root has also failed to prove effective in a large study.148
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.24 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.
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. Echinacea shows the most prevention promise for post-exercise infections.160 (Glutamine and vitamin C are also helpful for this specific purpose.)
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.25 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.26 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.27)
Four other studies also failed to find statistically significant preventive effects.90,91,118,169
A study often cited as evidence that echinacea can prevent colds actually found no benefit in the 609 participants taken on whole.92 Only by looking at subgroups of participants (a statistically questionable procedure) could researchers find any evidence of benefit, and it was still slight.
However, a recent study using a combination product containing echinacea, propolis, and vitamin C did find preventive benefits.119 In this double-blind, placebo-controlled study, 430 children ages 1 to 5 years were given either the combination or placebo for 3 months during the winter. The results showed a statistically significant reduction in frequency of respiratory infections. It is not clear which of the components of this mixture was responsible for the apparent benefits seen.
Until the 1930s, echinacea was the number one cold and flu remedy in the United States. It lost its popularity with the arrival of sulfa antibiotics. Ironically, sulfa antibiotics are as ineffective against colds as any other antibiotic, while echinacea does seem to be at least somewhat helpful. In Germany, echinacea remains the main remedy for minor respiratory infections.
Echinacea has shown promise for reducing the symptoms and duration of colds and aborting a cold once it has started. However, echinacea does not appear to be helpful for preventing colds, except in athletes (see Research Evidence). (Ginseng has shown strong prevention potential.) It may also not be effective in children.
Until the 1930s, echinacea was the number one cold and flu remedy in the United States. It lost its popularity with the arrival of sulfa antibiotics. Ironically, sulfa antibiotics are as ineffective against colds as any other antibiotic, while echinacea does seem to be at least somewhat helpful. In Germany, echinacea remains the main remedy for minor respiratory infections.
Echinacea has shown promise for reducing the symptoms and duration of colds and aborting a cold once it has started. However, echinacea does not appear to be helpful for preventing colds, except in athletes (see Research Evidence). (Ginseng has shown strong prevention potential.) It may also not be effective in children.
A signficant amount of research has been conducted to investigate the role of echinacea in preventing and treating the common cold.
Double-blind, placebo-controlled studies enrolling a total of more than 1,000 people have found that various forms and species of echinacea can reduce the symptoms and duration of a common cold, at least in adults.14-21,115,145
For example, in one double-blind, placebo-controlled trial, 80 individuals with early cold symptoms were given either E. purpurea extract or placebo.22 The results showed that individuals who were given echinacea recovered significantly more quickly: in just 6 days among the echinacea group versus 9 days among the placebo group.
Another double-blind, placebo-controlled trial looked at reduction of the severity of cold symptoms.23 The results in 246 participants showed that treatment with E. purpurea significantly improved cold symptoms such as runny nose, sore throat, sneezing, and fatigue. Symptom reduction with E. purpurea was also seen in a double-blind, placebo-controlled study of 282 people.115
In addition, three double-blind, placebo-controlled studies enrolling a total of about 600 participants found similar benefits with a combination product containing E. purpurea and E. pallida root, along with wild indigo and white pine.106-107,140-141
While the above evidence tends to suggest that the above-ground portion of E. purpurea is active against the common cold, two studies have failed to find benefit. One of these was a double-blind, placebo-controlled study enrolling 120 adults,116 the other an even larger trial (407 participants) involving children.117 The reason for these negative outcomes is not clear. E. angustifolia root has also failed to prove effective in a large study.148
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.24 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.
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. Echinacea shows the most prevention promise for post-exercise infections.160 (Glutamine and vitamin C are also helpful for this specific purpose.)
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.25 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.26 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.27)
Four other studies also failed to find statistically significant preventive effects.90,91,118,169
A study often cited as evidence that echinacea can prevent colds actually found no benefit in the 609 participants taken on whole.92 Only by looking at subgroups of participants (a statistically questionable procedure) could researchers find any evidence of benefit, and it was still slight.
However, a recent study using a combination product containing echinacea, propolis, and vitamin C did find preventive benefits.119 In this double-blind, placebo-controlled study, 430 children ages 1 to 5 years were given either the combination or placebo for 3 months during the winter. The results showed a statistically significant reduction in frequency of respiratory infections. It is not clear which of the components of this mixture was responsible for the apparent benefits seen.
There are three main species of echinacea: Echinacea purpurea, Echinacea angustifolia, and Echinacea pallida. A mixture containing all the parts of E. purpurea above the ground (flowers, leaves, stems) has the best supporting evidence for effectiveness in treating colds and flus;147 the root of E. purpurea is probably not effective, while the root of E. pallida may be the active part of that species.
Echinacea is generally thought to work by temporarily stimulating the immune system, although most (but not all) recent evidence has tended to cast doubt on this belief.104-105, 145-146 Contrary to popular belief, however, there is little reason to believe that echinacea strengthens or "nourishes" the immune system when taken over the long term. In other words, echinacea is effective for treating but not preventing illness.
Until the 1930s, echinacea was the number one cold and flu remedy in the United States. It lost its popularity with the arrival of sulfa antibiotics. Ironically, sulfa antibiotics are as ineffective against colds as any other antibiotic, while echinacea does seem to be at least somewhat helpful. In Germany, echinacea remains the main remedy for minor respiratory infections.
Echinacea has shown promise for reducing the symptoms and duration of colds and aborting a cold once it has started. However, echinacea does not appear to be helpful for preventing colds, except in athletes (see Research Evidence). (Ginseng has shown strong prevention potential.) It may also not be effective in children.
