Final answer:
The priority nursing intervention for a client experiencing an anaphylactic reaction is administering epinephrine.
Step-by-step explanation:
The priority nursing intervention for a client experiencing an anaphylactic reaction is administering epinephrine. Epinephrine is used to counteract the effects of anaphylaxis by raising blood pressure, relaxing bronchial smooth muscle, and reducing swelling in the airways. It helps to control the immune reaction until medical care can be provided. Epinephrine, also known as adrenaline, is a hormone and neurotransmitter that plays a crucial role in the body's "fight or flight" response to stress or danger. It is produced by the adrenal glands, which are located on top of each kidney.