A mouthpiece (10) is configured to be removably coupled with a nebulizer (12) to deliver nebulized medicament to the airway of a subject. The mouthpiece is configured to connect to the nebulizer in a swappable manner with another mouthpiece that is configured to operate in a continuous use mode. By contrast, the mouthpiece is configured to operate in a breath assist mode, a breath activated or dosimetric mode, and/or in other modes that reduce medicament waste caused, for example, by exhalation of the subject back into the mouthpiece. This may be advantageous during the delivery some medicaments (e.g., steroids, antibiotics, and/or other medicaments). The mouthpiece is configured to maintain the double venturi effect that would be provided by the continuous use mouthpiece.
