Which action should be taken immediately for a victim who reveals signs of anaphylaxis?

Administering an epinephrine auto-injector is the correct action to take immediately for a victim showing signs of anaphylaxis. Anaphylaxis is a severe and potentially life-threatening allergic reaction that can occur rapidly. The symptoms often include difficulty breathing, swelling of the throat, rapid swelling of the face or lips, and a drop in blood pressure, among others. In such a situation, epinephrine acts quickly to reverse these symptoms by constricting blood vessels, opening the airways, and increasing the heart rate, which can be life-saving.

Other actions, such as waiting for a doctor to arrive, would delay critical care. Providing water could potentially cause choking and does not address the underlying issue of anaphylaxis. Performing the Heimlich maneuver is inappropriate unless the victim is choking, which is not a typical symptom of anaphylaxis. Therefore, immediate administration of the epinephrine auto-injector is vital and should be the first step in managing a suspected anaphylactic reaction.