A dosing device comprising a dispenser (26) for dispensing a dose material and a dose actuation mechanism (44) is provided. The dose actuation mechanism (44) comprises a number of integrally hinged links (52, 54, 55) which are connected to each other at hinging points. A deflectable tongue (157), moveable in response to air flow from inhalation by a patient is attached to a first link (52), to move the first link in response to air flow, movement of the first link being transferred to a second link (54) to cause actuation of the dispenser. The first link rests at an over center, or stable, position prior to operation, and moves under center during operation of the device to trigger movement of the second link. The dose actuation mechanism is a one-piece moulding from plastics material.