A pushbutton for a system for dispensing a pressurized substance, the pushbutton including a body having a housing provided with an anvil around which a spray nozzle is mounted so as to form a substance dispensing path between the housing and a swirl array including a swirl chamber provided with a dispensing port as well as at least one supply duct for the chamber, the swirl chamber being defined by a side surface having a frusto-conical shape relative to which the supply duct(s) extend(s) in a transverse plane, the side surface tapering from an upstream end into which the downstream end of the supply duct(s) tangentially extends, to a downstream supply opening of the dispensing port, the dispensing port having an outlet size that is equal to the internal size of the downstream opening.