A disposable injector with a housing that has at least one compression hook, which has at least one support surface respectively in the region of its free end. A piston-actuating plunger rests on the support surface. The locking position of the compression hook is secured by an actuating element positioned in a locked position. The actuating element has a locked position, in which it rests securely on a sealing cap. The actuating element has a triggering position, which effects lateral retreat of the compression hook when the piston-actuating plunger is released.
