An aerosol generator device has an elongate body (1) with an interior passageway (6) extending longitudinally to its mouth end (4). The device receives an interchangeable, pressurised canister (2) charged with a nicotine containing liquid that is discharged in a metered doses on manual actuation of a trigger (39) that causes a valve in the canister to open and discharge through a discharge tube (13). Inner and outer collar members (18, 19) releasably couple the canister (2) with a controlled angular orientation to the body (1) with a bayonet action. The trigger (39) is rotatably mounted on the body about a trigger axis (40) spaced from and extending transversely of the longitudinal axis X-X of the device, and has a manually depressible surface portion (42) under a flexible cover (38), and a camming surface portion (43) that drives a slidable nozzle member (44) inwardly of the body to press the discharge tube (13) inwardly of the canister and the valve so as to form an aerosol from the liquid released from the canister.
