A dispenser includes a hollow containment body (2) able to be inserted in a bottle, having a hole (19) able to be positioned to face the interior of the bottle, a ring nut (14) able to be screwed on the neck of the bottle and having an annular shoulder (15) associated to, and covering, an annular lip (16) of the containment body (2) to mutually fasten ring nut (14) and containment body (2), at least one meatus (18) obtained in the containment body (2) to place selectively in fluid communication an inlet for air from the outside environment with the hole (19) in the containment body (2). The dispenser further includes spacer elements (20) active between the annular shoulder (15) and the annular lip (16) to define the air inlet passage.