A lock secured around an IV hub includes a hollow barrel having an open upper end with a pair of hinged gates therein that are pivotal between an open and a closed position. Below the gates are a pair of spring-biased flaps that prevent the gates from opening. When a key coupled with a syringe is inserted into slots formed on the gates and rotated, the flaps are forced outwardly, allowing the gates to open with a downward force so that the syringe can be coupled with the IV hub. When the key is rotated in an opposite direction, the flaps automatically pivot toward the center of the barrel and lift the gates to the original closed position.
