In its most recent supplement review, ConsumerLab.com, White Plains, NY, found that three of nine zinc pills or liquid supplements it tested contained only 73%-86% of claimed amounts. Among seven zinc lozenges, all contained the claimed amount of zinc, but most lacked instructions on their proper use. ConsumerLab.com also found that the labels on most zinc lozenges did not explain that they must be taken every two hours during the day to be effective against colds.