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, 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, 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").