Instructing the client to report any itching, swelling, or dyspnea.-because administration of blood or blood products may cause serious adverse effects such as allergic reactions, the nurse must monitor the client for these effects. signs and symptoms of life-threatening allergic reactions include itching, swelling, and dyspnea. although the nurse should inform the client of the duration of the transfusion and should document its administration, these actions are less critical to the clients immediate health. the nurse should assess vital signs at least hourly during the transfusion.