An inhaler for producing an inhalable aerosol of a powdered medicament includes an aerosolizing device in the form of a vortex chamber (1). The vortex chamber (1) has a curved wall (12), a tangential inlet port (3) and an axial exit port (2). The radius R of the vortex chamber (1) decreases with angular extend . The reduction in effective cross-sectional area of the vortex chamber accelerates the gas flow between the inlet (3) and the outlet (2) to reduce deposition of the medicament.