Echinacea purpurea for prevention of upper respiratory tract infections in children.

OBJECTIVE: The aim of this study was to determine whether Echinacea purpurea given to children for the treatment of acute upper respiratory tract infection (URI) was effective in reducing the risk of subsequent URI. DESIGN: This was a secondary analysis of data from a randomized, double-blind, placebo-controlled trial of Echinacea for the treatment of URI in children. SETTING: The study was conducted as a joint project between the Puget Sound Pediatric Research Network (Seattle, WA) and Bastyr University (Kenmore, WA). PARTICIPANTS: A total of 524 children ages 2 to 11 years were enrolled in the study. INTERVENTION: Children were monitored for URIs over a 4-month observation period during the fall/winters of 2000-2001 and 2001-2002. At entry the children were randomized to receive Echinacea or placebo to treat acute URIs during the observation period. MAIN OUTCOME MEASURES: The occurrence of a second URI and the number of days between the end of the first URI and the start of the second URI was ascertained. Survival and Cox regression analyses were used to determine whether children who took Echinacea for their URIs were less likely to develop subsequent URIs. RESULTS: Among the 401 children with at least one URI treated with study medication, 69.2% of those receiving placebo developed a second URI versus 55.8% of those who received Echinacea. Use of Echinacea was associated with a 28% decreased risk of subsequent URI (p = 0.01, 95% confidence interval 8%-44% decreased risk). CONCLUSIONS: Echinacea purpurea may be effective in reducing the occurrence of subsequent URIs in children. However this finding needs to be replicated in a URI prevention trial.