Barrett et al. (Ann Intern Med 2010;153:769-777) enrolled subjects within 36 hours of illness onset, and administered echinacea tablets (or placebo) containing 675 mg E. purpurea root standardized to 2.1 mg alkamides and 600 mg E. angustifolia root standardized to 2.1 mg alkamides. Subjects consumed two tablets at enrollment, followed by two-tablet doses three more times within 24 hours of enrollment. Dosing then went to one tablet four times daily for the next four days. Thus, each participant ingested the equivalent of 10.2 g of dried echinacea root during the first 24 hours and the equivalent of 5.1g during each of the next four days. Results were in the direction of benefit, amounting to an average half day reduction in the duration of a week-long cold, or an approximate 10% reduction in overall severity.