What action should a nurse take if a client is experiencing a severe allergic reaction?

In the case of a severe allergic reaction, also known as anaphylaxis, the most critical and immediate action to take is to administer epinephrine as prescribed. Epinephrine is a life-saving medication that works quickly to reverse severe allergic reactions by constricting blood vessels, relaxing airway muscles, and improving heart function. The timely administration of epinephrine can significantly reduce the risk of severe complications or death associated with anaphylaxis.

The other options do not address the immediate life-threatening nature of the situation. Providing solid food is inappropriate because the client may be experiencing difficulty swallowing or their airway may be compromised. Applying ice to an affected area may offer some relief for localized reactions but is not effective in treating systemic symptoms or restoring airway patency. While instructing the client to remain calm may be beneficial for anxiety, it does not treat the underlying physiological changes occurring during a severe allergic reaction and should not be the primary intervention in an emergency situation.