by Jackie Hart, MD
Q: Does echinacea really work for treating or preventing colds? Are there any side effects from echinacea?
A: Echinacea purpurea is a plant used by Native Americans for the treatment of respiratory infections. During the last 5-10 years there has been increasing interest in the use of echinacea to prevent or treat the common cold. Fortunately, there has been a significant amount of research conducted on this topic.
The results of many studies look very promising regarding echinaceas ability to bolster immunity. Several "test tube" studies (those conducted in test tubes, rather than in people) have shown increased immune activity against organisms that cause infection and tumor cells that cause cancer.
The real question, however, is whether these test tube findings translate into effectiveness in people. And even if immunity is enhanced, does this lead to reduced frequency or intensity of infections? Two recent studies that have received a fair amount of publicity say no.
One study followed 109 patients for eight weeks; each of these patients had reported at least three infections from the preceding cold and flu season and were randomized to receive either echinacea or a placebo. Although there was a tendency toward fewer infections and shorter duration of infections in people who received echinacea, the results were not "statistically significant," meaning the scientists could not conclude from them that echinacea was effective in preventing infections.
Similarly, a 12-week study of 302 people who received either echinacea or placebo found a tendency toward fewer infections of shorter duration, but this trend was also not statistically significant. One interesting finding of this study, however, is that the people who took echinacea, although they did not know if they were taking echinacea or placebo, reported feeling better overall than those who did not. This is important, because if you have a cold but feel better overall, you may still be able to do your usual activities.
The authors of this study suggest that further study with larger groups of people is necessary. In fact, a study published earlier this year of 559 otherwise healthy adults who had colds did show certain forms of echinacea to be more effective than a placebo in decreasing the duration and intensity of symptoms.
The results of these three studies may differ because the first two were studying the effect of echinacea in preventing colds, while this last one studied the effect of echinacea in treating colds.
Regarding the safety and potential side effects of echinacea, animal studies have not shown adverse side effects from taking echinacea. Last year, however, an epidemiologic study of humans suggested that use of echinacea may be associated with infertility.
Since reading the infertility study, I advise women who would like to get pregnant and their male partners to avoid taking echinacea.
I suggest that if you are considering using echinacea, it is likely to be safe in most cases, but you should discuss this with your doctor.
Q: Does echinacea really work for treating or preventing colds? Are there any side effects from echinacea?
A: Echinacea purpurea is a plant used by Native Americans for the treatment of respiratory infections. During the last 5-10 years there has been increasing interest in the use of echinacea to prevent or treat the common cold. Fortunately, there has been a significant amount of research conducted on this topic.
The results of many studies look very promising regarding echinaceas ability to bolster immunity. Several "test tube" studies (those conducted in test tubes, rather than in people) have shown increased immune activity against organisms that cause infection and tumor cells that cause cancer.
The real question, however, is whether these test tube findings translate into effectiveness in people. And even if immunity is enhanced, does this lead to reduced frequency or intensity of infections? Two recent studies that have received a fair amount of publicity say no.
One study followed 109 patients for eight weeks; each of these patients had reported at least three infections from the preceding cold and flu season and were randomized to receive either echinacea or a placebo. Although there was a tendency toward fewer infections and shorter duration of infections in people who received echinacea, the results were not "statistically significant," meaning the scientists could not conclude from them that echinacea was effective in preventing infections.
Similarly, a 12-week study of 302 people who received either echinacea or placebo found a tendency toward fewer infections of shorter duration, but this trend was also not statistically significant. One interesting finding of this study, however, is that the people who took echinacea, although they did not know if they were taking echinacea or placebo, reported feeling better overall than those who did not. This is important, because if you have a cold but feel better overall, you may still be able to do your usual activities.
The authors of this study suggest that further study with larger groups of people is necessary. In fact, a study published earlier this year of 559 otherwise healthy adults who had colds did show certain forms of echinacea to be more effective than a placebo in decreasing the duration and intensity of symptoms.
The results of these three studies may differ because the first two were studying the effect of echinacea in preventing colds, while this last one studied the effect of echinacea in treating colds.
Regarding the safety and potential side effects of echinacea, animal studies have not shown adverse side effects from taking echinacea. Last year, however, an epidemiologic study of humans suggested that use of echinacea may be associated with infertility.
Since reading the infertility study, I advise women who would like to get pregnant and their male partners to avoid taking echinacea.
I suggest that if you are considering using echinacea, it is likely to be safe in most cases, but you should discuss this with your doctor.