Duration reductions ( mean 0 days , median 0 . 43 days ) for multi - ligand ZG and ZA lozenges differed significantly from duration reductions ( mean 3 . 37 days , median 2 . 9 days ) for single ligand ZA and ZG lozenges ( P < 0 . 001 ) showing that additive ligands as flavor - masks damaged or eliminated efficacy .