A syringe propellable by propellant that boils at a predetermined temperature, the syringe including a barrel having an outlet at a front end, and a stopper axially moveable in the barrel. The stopper separates a first chamber and a second chamber, the first chamber being axially forwards of the stopper and being configured for containing a medicament, and the second chamber being axially rearwards of the stopper and being configured to receive propellant for acting on the stopper to move the stopper axially forwardly in the barrel to expel medicament through the outlet upon actuation of the syringe. The syringe further includes a rupturing portion and a third chamber for containing propellant where the third chamber is rupturable upon actuation of the syringe to fluidly connect the third chamber to the second chamber. When propellant is released into the second chamber the pressure in the second chamber increases causing the stopper to move axially forwardly to begin expulsion of medicament from the first chamber through the outlet. The syringe is configured such that while the medicament is expelled from the first chamber the pressure in the second chamber changes to a second pressure.
