A breath-responsive inhaler having a trigger mechanism for triggering delivery of a medicament to a user, the trigger mechanism including a medicament source, having a primed position in which the inhaler is primed for use and an actuated position in which the medicament source is actuated to dispense a dose of medicament, a toggle mechanism for selectively permitting movement of the source from its primed position to its actuated position, the toggle mechanism comprising a vane positioned in the air flow path, the vane being pivoted about a vane pivot, and wherein the trigger mechanism is triggered by movement of the vane upon inhalation of the user to move the toggle mechanism between a primed condition in which the medicament source is maintained in its primed position by cooperation with the toggle mechanism and an actuated condition in which the toggle mechanism is disengaged from cooperation with the medicament source
