The pain in the arm after blood donation may be due to the puncture site not being completely repaired, and there may be slight pain in the local area, or there may be inflammation in the puncture site or other causes of pain in the arm. If there is no obvious abnormality in the appearance and the pain is not serious, you can take a rest and avoid exerting force on the local area for the time being. If it is obvious that the puncture site is red and swollen, it is necessary to go to the hospital to see the doctor, who will make a preliminary judgment with the physical examination. If it is the inflammation of the puncture point, timely anti-inflammatory drugs, such as cephalosporin and other anti-infective treatment, the local area can be disinfected with iodophor, but also with the external application of magnesium sulfate, to help reduce inflammation and pain.