Dispensing head (6") for a trigger dispenser (1"), applicable to a bottle containing a product to be dispensed, comprising: - a frame for supporting components of the dispensing head, having a functional zone (22") comprising a first reference plane (26"), a frame port , a suction outlet port and a dispensing inlet port opening on said functional zone ; - a pressure chamber operatively connected to the frame port ; - a trigger to pressurize the product present in the pressure chamber ; - a suction duct ending with the suction outlet port for transporting the product suctioned from the bottle; - a dispensing duct which extends from the dispensing inlet port along a dispensing axis (W), for dispensing the product to the external environment; - valve means applied to the functional zone (22"), comprising a suction shutter cooperating with the suction outlet port and a dispensing shutter cooperating with the dispensing inlet port so as to carry out a precompression of the product before dispensing; wherein said valve means (50") cooperate with the first plane of the frame (10") to form a precompression chamber upstream of the dispensing inlet port , which can be fed by the product exiting from the frame port , wherein said functional zone comprises an annular chamber wall (51"), at least partially delimiting said precompression chamber , characterised in that the annular chamber wall (51") is provided with openings (53") passing through the thickness, surrounding the dispensing inlet port , and that the valve means comprise a valve body (52") provided with a membrane (110") which delimits at the top said precompression chamber (59"), resting on the annular chamber wall (51"). - a frame for supporting components of the dispensing head, having a functional zone (22") comprising a first reference plane (26"), a frame port , a suction outlet port and a dispensing inlet port opening on said functional zone ; - a pressure chamber operatively connected to the frame port ; - a trigger to pressurize the product present in the pressure chamber ; - a suction duct ending with the suction outlet port for transporting the product suctioned from the bottle; - a dispensing duct which extends from the dispensing inlet port along a dispensing axis (W), for dispensing the product to the external environment; - valve means applied to the functional zone (22"), comprising a suction shutter cooperating with the suction outlet port and a dispensing shutter cooperating with the dispensing inlet port so as to carry out a precompression of the product before dispensing; wherein said valve means (50") cooperate with the first plane of the frame (10") to form a precompression chamber upstream of the dispensing inlet port , which can be fed by the product exiting from the frame port , wherein said functional zone comprises an annular chamber wall (51"), at least partially delimiting said precompression chamber , characterised in that the annular chamber wall (51") is provided with openings (53") passing through the thickness, surrounding the dispensing inlet port , and that the valve means comprise a valve body (52") provided with a membrane (110") which delimits at the top said precompression chamber (59"), resting on the annular chamber wall (51"). <EOS>