According to a study published online and in the July edition of The Lancet Infectious Diseases, the herbal product echinacea could cuts the chances to catch a common cold by 58 percent and reduces the duration of the common cold by 1.4 days.

Dr Craig Coleman, University of Connecticut School of Pharmacy, Hartford Hospital, Connecticut, USA, and colleagues have conducted a meta-analysis of 14 studies into the use of echinacea to relieve/protect against catching a cold.

The term echinacea refers to parts taken from nine related plant species indigenous to North America and Echinacea angustifolia, Echinacea pallida, and Echinacea purpurea are the most common species recognized for their medicinal value

After studying more then 1600 patients the authors  conclude: "An analysis of the current evidence in the literature suggests that echinacea has a benefit in decreasing the incidence and duration of the common cold; however, large-scale randomized prospective studies controlling for variables such as species, quality of preparation and dose of echinacea, method of cold induction, and objectivity of end points evaluated are needed before echinacea for the prevention or treatment of the common cold can become standard practice."

The authors found that if echinacea was used in attempt to prevent "natural" catching of a cold, it reduced cold incidence by 65%; but if patients were directly inoculated with the cold-causing rhinovirus, echinacea use only reduced cold incidence by 35%. The authors say: "With over 200 viruses capable of causing the common cold, echinacea could have modest effect against rhinovirus but marked effects against other viruses."