A client is receiving 2 units of packed red blood cells for…

A client is receiving 2 units of packed red blood cells for anemia (Hgb of 8.2 g/dL ). Twenty minutes into the first transfusion, the client has a flushed face, hives over upper body trunk, and is reporting pain in lower back. His vital signs include pulse rate of 110 and BP drop to 95/56. What is the priority action?