A dual lumen IV administration set includes a first lumen having an inner diameter of a first value. A second lumen is paired with the first lumen, and the second lumen has an inner diameter of a second value that is greater than the first value. A flow merger merges flow output from a distal end of the first lumen and flow output from a distal end of the second lumen to form a single flow output in an exit lumen. An injection port intersects the first lumen, thereby providing injection access to flow therethrough, prior to merging with the flow output of the second lumen.