Abstract: The present invention relates to air-flow in a nebulizer head. In order to provide a nebulizer head with an improved air-flow guidance, a nebulizer head (10) comprises a housing structure (12) providing an air-flow path (16) with two opposite air-flow openings (18a, 18b), and a fluid reservoir (14) provided to accommodate a liquid from which small droplets are to be generated in order to form an aerosol, and an aerosol generator (20) with an aperture member (22) that comprises an aperture surface (24) with a plurality of apertures to provide the small droplets from the liquid. The fluid reservoir is arranged adjacent the aerosol generator such that the aperture member is in contact with the fluid. The aerosol generator is arranged within the air-flow path. At least one by-pass flow path (26) is provided between the aerosol generator and the housing structure. The air-flow path is a bidirectional path that provides a first air-flow direction (28) for inhaling, and a second air-flow direction (38) for exhaling.