Redness of the infusion vessels is actually a sign of superficial phlebitis. In the vast majority of patients, the stimulation of drugs after infusion, the change of osmotic pressure in the vessels due to high concentration of drugs and the stimulation of foreign bodies such as indwelling needles can lead to the generation of intravascular inflammation due to the relatively small superficial veins. This inflammation is not clinically known as septic inflammation, but rather aseptic inflammation, which can lead to narrowing or even occlusion of the lumen of the tiny veins and induce the formation of superficial venous thrombosis. Once the thrombus is formed, causing obstruction of vascular reflux, it can cause local inflammatory manifestations. The first and foremost is the reddening of the infusion vessels, which in addition to local reddening, can also be associated with pain, fever, and swelling. Even some patients will go along the blood vessels and form the reddening of the vessels. It means that this phlebitis, which has a deeper and wider involvement, will be involved along the vascular alignment. Once this condition develops, it needs to be seen systematically in a specialized vascular surgery department.