Abstract: A needle-free injection system may include an active substance cartridge, which may have a nozzle and a plunger-actuated dosing chamber for the pressurized dispensing of an active substance. The injection device may have a housing with a receptacle for accommodating the active substance cartridge and a piston, which may be movable relative to the housing and may be designed to execute a movement for the ejection of the active substance from the active substance cartridge, where a mechanism for driving the plunger may be provided, and the plunger may have a starting position related to the mechanism, from which position the piston may be released to move by means of a trigger. The mechanism may be designed to allow the piston to return to the starting position. The dispensing quantity of the active substance may be adjustable.