An adapter includes: a first connection connected to a mouthpiece, a second connection in communication with the first connection, receiving an aerosol, and delivering the aerosol to a patient, a third connection receiving breathable air from a source, a connector located between the first and second connection such that the connector is in fluidic association with an expulsion nozzle of a nebulizer when the first connection is connected to the nebulizer, the connector receiving the aerosol dispensed from the expulsion nozzle and conveying the aerosol to the second connection, where the first connection is connectible in a leak-tight manner to at least one of the expulsion nozzle and a projection that surrounds the expulsion nozzle, so that no supply air or breathable air can flow past the expulsion nozzle through or into the first connection, thereby closing off air supply openings of the nebulizer.
