Echinacea is a popular herbal treatment for the common cold, but its efficacy continues to be debated.
Participants included 719 patients; 713 completed the protocol. Mean age was 33.7 years; 64 percent were female; 88 percent were White. Patients were assigned to one of four groups: 1) no pills, 2) placebo pills (blinded), 3) echinacea pills (blinded), 4) echinacea pills (unblinded, open-label).
In this randomized, controlled trial, illness duration and severity did not significantly decrease in participants who received either blinded or open-label echinacea compared with those who received blinded placebo or no pills.
Although this study suggests that echinacea is ineffective at reducing cold symptoms or duration, higher-than-expected variability in cold symptoms limited its power to provide a definitive answer to the question about the effectiveness of echinacea.