Though sucking zinc lozenges has been promoted as a treatment for the common cold, research has revealed no consistent effect  Recently, however, a zinc gel applied nasally has been shown to greatly reduce the duration of colds
Since the gel contains zinc in the same form and concentration as the lozenges, the greater effectiveness of the gel must be due to the fact that cold viruses tend to concentrate in the nose, not the mouth
The mechanism by which zinc affects the viruses that cause the common cold has not been conclusively established.