Investigators led by Bruce Barrett, MD, PhD, an associate professor of family medicine at the University of Wisconsin School of Medicine and Public Health, studied 719 children, women, and men ages 12 to 80 who lived in Wisconsin. Twelve percent of the group were smokers; the average age was around 33. Sixty-four percent of the group were female and 88% were white.
The study participants were randomly assigned to either not take anything for their cold, take a pill containing echinacea, or take a placebo pill. Some of the patients were told what they were taking and some were not told. Patients had to record their symptoms twice a day over the course of no more than two weeks.
Overall, patients taking echinacea experienced a slightly reduced duration of their cold of about seven to 10 hours less than those not taking echinacea. Their colds were also slightly less severe. However, the researchers note that they can’t rule out whether these mild improvements were the result of chance or other factors.
The investigators also measured levels of immune cell activity from nasal wash samples provided by the participants. The samples did not show any significant differences between those who took echinacea and those who didn’t, suggesting there wasn’t a major effect on the immune system.
“The pharmacological activity of Echinacea probably has only a small beneficial effect in persons with the common cold,” Barrett and his team write. “Individual choices about whether to use Echinacea to treat the common cold should be guided by personal health values and preferences, as well as by limited evidence available."
The study was funded by the National Center for Complementary and Alternative Medicine at the National Institutes of Health, and the findings are published in the Dec. 20 issue of Annals of Internal Medicine.
Echinacea has long been touted for its properties in fighting upper respiratory infection. Evidence about its effectiveness has been mixed. Acute upper respiratory infection is one of the top 10 most expensive illnesses in the U.S., according to the researchers, resulting in an economic cost of $40 billion per year, as well as 20 million doctor visits and 40 million lost school days and workdays.