What is the first step after noticing a person displaying signs of anaphylaxis?

The first step after noticing a person displaying signs of anaphylaxis is to activate emergency medical services (EMS). Anaphylaxis is a severe, potentially life-threatening allergic reaction that can escalate rapidly. It requires immediate medical attention and, often, the administration of epinephrine. While administering oxygen may be necessary later in the process if the person's breathing worsens, it is not the first action taken. Providing water is inappropriate as the individual may have difficulty swallowing or may require immediate medical intervention rather than hydration. Performing CPR is only relevant if the person becomes unresponsive and is not breathing, which would be a consequence of anaphylaxis. The prioritization of notifying EMS ensures that the victim receives the specialized medical care as quickly as possible.