What is the first step a lifeguard should take in the event of a severe allergic reaction?

The first step a lifeguard should take in the event of a severe allergic reaction is to administer an epinephrine auto-injector if available. This is because a severe allergic reaction, also known as anaphylaxis, can be life-threatening and requires immediate intervention. Epinephrine serves to counteract the severe symptoms of anaphylaxis by constricting blood vessels, increasing blood pressure, and opening the airways to improve breathing. Administering the auto-injector as soon as possible can be crucial in stabilizing the person's condition until further medical help arrives.

While other actions, like calling for help, are important steps in the emergency response sequence, they should not delay the administration of epinephrine. Waiting to see if the reaction progresses before taking action can lead to serious complications or even be fatal. Therefore, having the knowledge and readiness to use an epinephrine auto-injector effectively places immediate care at the forefront of responding to severe allergic reactions.