A trigger dispensing head for a dispensing device, comprising: - a frame applicable to a bottle of the dispensing device; - a manually-operable trigger; - a piston chamber supported by the frame and a piston sealingly slidable in the piston chamber along a piston axis through actuation by the trigger; - a dispensing duct, ending with a dispensing end, in communication with the piston chamber to take the product being dispensed from the piston chamber towards the external environment; - a suction duct in communication with the piston chamber to take the product being suctioned from the bottle to the piston chamber; - suction valve means adapted to operate between the piston chamber and the suction duct to allow the passage of the product being suctioned from the bottle to the piston chamber during the suction step and to prevent the product from returning from the piston chamber to the bottle during the dispensing step; - a locking member positioned on the trigger; - a nozzle engaged to the frame having a nozzle axis, comprising: i) a base positioned at the dispensing end, provided with a nozzle passageway and an outer port; ii) an annular gripping wall extending from the base; iii) an actuation compartment located on the gripping wall, suitable for receiving the locking member; iv) an interference element positioned on the gripping wall; wherein the nozzle is positionable in a closing position, in which the locking member engages the interference element preventing the actuation stroke of the trigger, and in an opening position, in which the locking member is freely movable in the actuation compartment allowing the actuation stroke of the trigger; wherein the nozzle comprises at least one backing wall (71, 73) radially protruding internally from the gripping wall, configured to form a limit stop for the locking member upon reaching the closing position and/or the opening position. - a frame applicable to a bottle of the dispensing device; - a manually-operable trigger; - a piston chamber supported by the frame and a piston sealingly slidable in the piston chamber along a piston axis through actuation by the trigger; - a dispensing duct, ending with a dispensing end, in communication with the piston chamber to take the product being dispensed from the piston chamber towards the external environment; - a suction duct in communication with the piston chamber to take the product being suctioned from the bottle to the piston chamber; - suction valve means adapted to operate between the piston chamber and the suction duct to allow the passage of the product being suctioned from the bottle to the piston chamber during the suction step and to prevent the product from returning from the piston chamber to the bottle during the dispensing step; - a locking member positioned on the trigger; - a nozzle engaged to the frame having a nozzle axis, comprising: i) a base positioned at the dispensing end, provided with a nozzle passageway and an outer port; ii) an annular gripping wall extending from the base; iii) an actuation compartment located on the gripping wall, suitable for receiving the locking member; iv) an interference element positioned on the gripping wall; wherein the nozzle is positionable in a closing position, in which the locking member engages the interference element preventing the actuation stroke of the trigger, and in an opening position, in which the locking member is freely movable in the actuation compartment allowing the actuation stroke of the trigger; wherein the nozzle comprises at least one backing wall (71, 73) radially protruding internally from the gripping wall, configured to form a limit stop for the locking member upon reaching the closing position and/or the opening position. i) a base positioned at the dispensing end, provided with a nozzle passageway and an outer port; ii) an annular gripping wall extending from the base; iii) an actuation compartment located on the gripping wall, suitable for receiving the locking member; iv) an interference element positioned on the gripping wall; wherein the nozzle is positionable in a closing position, in which the locking member engages the interference element preventing the actuation stroke of the trigger, and in an opening position, in which the locking member is freely movable in the actuation compartment allowing the actuation stroke of the trigger; wherein the nozzle comprises at least one backing wall (71, 73) radially protruding internally from the gripping wall, configured to form a limit stop for the locking member upon reaching the closing position and/or the opening position.