An inhaler is disclosed for dispensing a dose of an active agent to the respiratory tract of a patient. The inhaler comprises a housing defined by an upper part (150) and a lower part (100) and a mouthpiece (900) which is attached to or is adapted to be attached to the housing. The housing includes a means for storing an active agent and an airway for delivering the dose to the mouthpiece (900) in a stream of air or other gas. The upper part (150) and the lower part (100) of the housing are joined together by a mechanical fixing means and are sealed together by a separate sealing portion. The sealing portion comprises a flange provided on one of the upper part or the lower part of the housing and a slot provided on the other part of the housing. The flange is adapted to fit sealingly into the slot.
