Why was this study done?

The common cold is a viral illness that is spread by contagion. While it is rarely fatal, it does account for a large amount of discomfort, suffering, and loss of productivity. This study was designed to help define the role of a herbal remedy containing Echinacea in the treatment of the common cold.

What did the study find?

Supplementing with Echinacea (six dosages on day one, followed by three dosages every day after) in 148 students with recent-onset colds was not effective at reducing duration or severity of illness.

Treatment of the common cold with unrefined Echinacea. A randomized, double-blind, placebo-controlled trial.
Authors: Barrett BP, Brown RL, Locken K, Maberry R, Bobula JA, D’Alessio D. Ann Intern Med. 2002 Dec 17;137(12):939-46.
PubMed Citation, PMID: 12484708.
PDF Manuscript: Ann Intern Med 2002.