There is disclosed a precharged disposable syringe consisting of a housing having a central aperture through which extends an actuator button to contact an internal piston mounted over a medication ampoule contained in the housing. The ampoule includes a dependent hypodermic needle and the ampoule is slightively mounted in the housing for movement between a recessed position where it is totally contained and supported within the housing and an extended position with the dependent needle projecting out of the housing. An actuator spring is located in the housing and is compressed and biased to move the piston and the ampoule into the projected position. Medication is discharged by the mechanically coupled actuator button and piston. The actuator button and piston is locked for safety with a dent and plastic ring.