Abstract: The invention is a disposable medical safety syringe. The syringe consists of a hollow cylindrical, lens-shaped body; a corresponding plunger rod with a lens-shaped piston head on the anterior of the rod and a flattened base on the posterior of the shaft where thumb pressure is applied during injection; and a sharp, hollow needle secured to the anterior of the syringe body. The piston is manufactured to create a tight hydraulic seal while allowing for free movement of the piston within the hollow syringe body during both fill and injection. The point of connection between the piston and the rod is such to allow the rod to break away from the piston when the rod is twisted within the hollow syringe body as the piston is held securely in place due to its lens shape which corresponds to the lens shape of the hollow syringe outer body.