An aerosol generator device comprises an elongate body with an interior passageway extending longitudinally to its mouth end. The device receives an interchangeable, pressurised canister charged with a nicotine containing liquid that is discharged in a metered dose on manual actuation of a trigger that causes a valve in the canister to open and discharge through a discharge tube. Inner and outer collar members releasably couple the canister with a bayonet action. The trigger is rotatably mounted on the body about a trigger axis spaced from and extending transversely of the longitudinal axis of the device, and has a manually depressible surface portion under a flexible cover, and a camming surface portion that drives a slidable nozzle member inwardly of the body to press the discharge tube inwardly of the canister and the valve so as to form an aerosol from the liquid released from the canister.