Cold season will soon be upon us(in the Northern hemisphere), so it helps to know what may help prevent or treat this common illness. One of the most popular cold remedies is the herb echinacea, a member of the daisy or asteraceae family. But does it really help?
According to the University of Connecticut School of Pharmacy, Storrs, CT, USA, in Evaluation of echinacea for the prevention and treatment of the common cold: a meta-analysis:
Echinacea is one of the most commonly used herbal products, but controversy exists about its benefit in the prevention and treatment of the common cold. Thus, we did a meta-analysis evaluating the effect of echinacea on the incidence and duration of the common cold. 14 unique studies were included in the meta-analysis. Incidence of the common cold was reported as an odds ratio (OR) with 95% CI, and duration of the common cold was reported as the weighted mean difference (WMD) with 95% CI. Weighted averages and mean differences were calculated by a random-effects model (DerSimonian-Laird methodology). Heterogeneity was assessed by the Q statistic and review of L’Abbé plots, and publication bias was assessed through the Egger weighted regression statistic and visual inspection of funnel plots. Echinacea decreased the odds of developing the common cold by 58% (OR 0.42; 95% CI 0.25-0.71; Q statistic p<0.001) and the duration of a cold by 1.4 days (WMD -1.44, -2.24 to -0.64; p=0.01). Similarly, significant reductions were maintained in subgroup analyses limited to Echinaguard/Echinacin use, concomitant supplement use, method of cold exposure, Jadad scores less than 3, or use of a fixed-effects model. Published evidence supports echinacea’s benefit in decreasing the incidence and duration of the common cold.
Impressive, so it appears to have helped. But wait, here’s another look, from the Cochrane Database(2006), a study done at the Centre for Complementary Medicine Research, Kaiserstrasse 9, Munich, Germany, Echinacea for preventing and treating the common cold:
Echinacea preparations tested in clinical trials differ greatly. There is some evidence that preparations based on the aerial parts of Echinacea purpurea might be effective for the early treatment of colds in adults but results are not fully consistent. Beneficial effects of other Echinacea preparations, and for preventative purposes might exist but have not been shown in independently replicated, rigorous randomized trials.
And another, from the University of Wisconsin, Madison, Wisconsin 53715, USA, Echinacea for treating the common cold: a randomized trial:
Illness duration and severity were not statistically significant with echinacea compared with placebo. These results do not support the ability of this dose of the echinacea formulation to substantively change the course of the common cold.
This one is clearly negative. This is just a small sample of many echinacea studies. I encourage you to read through the literature yourself if you are curious about echinacea. But overall, based on these studies and many others, the evidence is mostly negative to mixed for echinacea. If I had a cold, I wouldn’t take it.