An inhaler comprising a reservoir (5) of an inhalable composition. A housing (I) contains the reservoir and has an outlet end and an opposite end. A composition flow path (13) for the flow of the composition extends from the reservoir along the flow path and out of a composition outlet at the outlet (II) end of the housing. A flexible diaphragm (16) within the housing defines an air flow path from an air inlet (25) to an air outlet (9) at the outlet end of the housing, the diaphragm extending past the air flow inlet towards the opposite end separating the air flow path on one side of the diaphragm from the remainder of the housing on the opposite side of the diaphragm. A valve element (15) is movable with the diaphragm (16).