Immunoglobulin is tough on veins and phlebitis is, unfortunately rather common. As others say, using larger veins if possible, changing veins, and drinking well can help as can slightly slowing the rate of infusion. I had the same IV for four days before and the vein was not happy on the last day. Warm packs and freedom to let my hand move helped a lot. If one keeps using a vein after it starts getting phlebitis, the vein can get inflammed enough that it clots. Often if you let that vein rest, it may recover and you can use it again.
WithHope for a cure of these diseases