After the infusion of fluids, the pain in the arm on the side of the infusion should be considered to have a higher possibility of phlebitis, which is mostly caused by the infusion of liquids with higher concentration or higher acidity through the superficial vein, and the common liquids with phlebitis are fat milk preparation and amino acid preparation, as well as liquids containing higher concentration of potassium ions and sodium ions. If the patient shows phlebitis, the patient can be given topical magnesium sulfate solution or mannitol solution to reduce local edema and inflammatory reaction, and the patient’s pain can be improved quickly.