Preparations of the plant Echinacea are widely used in some European countries and in North America for common colds. Echinacea preparations available on the market differ greatly as different types (species) and parts (herb, root, or both) of the plant are used, different manufacturing methods (drying, alcoholic extraction, or pressing out the juice from fresh plants) are used, and sometimes also other herbs are added. We reviewed 16 controlled clinical trials investigating the effectiveness of several different Echinacea preparations for preventing and treating common colds. Two trials investigated whether taking Echinacea preparations for 8 to 12 weeks prevents colds but found no clear effect. The majority of trials investigated whether taking Echinacea preparations after the onset of cold symptoms shortens the duration or decreases the severity of symptoms, compared with placebo. It seems that some preparations based on the herb of Echinacea purpurea might be effective for this purpose in adults, while there is no clear evidence that other preparations are effective or that children benefit. Side effects were infrequent but rashes were reported in one trial in children.
Echinacea for preventing and treating the common cold
October 7, 2009