Depending on the total dosage of zinc and the composition of lozenges, zinc lozenges may shorten the duration of common cold episodes by up to 40%.  Harri Hemila, from University of Helsinki (Finland), completed a meta-analysis of placebo-controlled trials that have examined the effect of zinc lozenges on natural common cold infections. Of the 13 trial comparisons identified, five used a total daily zinc dose of less than 75 mg and uniformly those five comparisons found no effect of zinc. Three trials used zinc acetate in daily doses of over 75 mg, with the average indicating a 42% reduction in the duration of colds. Five trials used zinc salts other than acetate in daily doses of over 75 mg, with the average indicating a 20% decrease in the duration of colds. Concluding that: “This study shows strong evidence that the zinc lozenge effect on common cold duration is heterogeneous so that benefit is observed with high doses of zinc but not with low doses,” the study author urges that: “The effects of zinc lozenges should be further studied to determine the optimal lozenge compositions and treatment strategies.”