Effectiveness of an herbal preparation containing echinacea, propolis, and vitamin C in preventing respiratory tract infections in children: a randomized, double-blind, placebo-controlled, multicenter study.

Objective: To evaluate the effectiveness and safety of a preparation containing echinacea, propolis, and vitamin C in the prevention of respiratory tract infections in children during a 12-week winter period.

Design: Randomized, double-blind, placebo-controlled study.

Subjects: Four hundred thirty children, aged 1 to 5 years, were randomized to an herbal extract preparation (n = 215) or a placebo elixir (n = 215).