A jet injector that includes a prefilled syringe (18). The syringe includes afluid chamber (22) that contains a medicament. The syringe also has aninjection-assisting needle (24), and a plunger is movable within the fluidchamber. A housing is configured for allowing insertion of the needle to apenetration depth. An energy source is configured for biasing the plunger toproduce an injecting pressure in the medicament in the fluid chamber ofbetween about 80 and 1000 p.s.i. to jet inject the medicament from the fluidchamber through the needle to an injection site.
