A hardened and bulging blood vessel after infusion is considered to be phlebitis caused by infusion. Venous vasculitis refers to acute severe or aseptic inflammation of venous blood vessels, which can be categorized into superficial phlebitis and deep phlebitis according to different lesion sites. Repeated infusion of fluids for a long time has an irritating effect on the blood vessels, which can easily cause hardening and bulging of the blood vessels after infusion, often manifested as local skin redness and swelling, elevated skin temperature, tenderness, and a hard striated sensation can be felt. When these symptoms appear, first of all, should stop the infusion in the venous blood vessels suffering from vasculitis, external magnesium sulfate anti-inflammatory de-swelling, can be treated with hot compresses at home. At the same time, during the treatment period, we should observe whether the patient has superficial vein thrombosis, because phlebitis often causes superficial vein thrombosis, once venous thrombosis occurs, we should give active anticoagulation treatment. If the blood vessels harden and bulge after infusion, please treat them under the guidance of the doctor in time.