What it means
As a medication route, IJ for "injection" has been misread as IV or as "intrajugular," so ISMP lists it as error-prone: write "injection." In notes about central lines and procedures, IJ commonly names the internal jugular vein in the neck, a common site for central venous catheters ("right IJ triple-lumen catheter").
For the nurse
Never use IJ for a drug route. When reading "IJ" about a central line, it refers to the neck vein; ask if it is unclear.