A retractable needle is provided for a syringe comprising a barrel and a plunger that comprises a portion capable of engaging the retractable needle for retraction. The retractable needle comprises a cannula, a needle body having a plunger-engaging member, at least one aperture and an elongate portion which houses the cannula, the cannula comprising an end which is in fluid communication with the at least one aperture, wherein the at least one aperture is located between the plunger-engaging member and the elongate portion. The positioning of the at least one aperture distal to the plunger-engaging member maximizes the efficiency of fluid delivery.
