What is an appropriate response when a casualty is showing signs of an anaphylactic reaction?

In the case of an anaphylactic reaction, the most critical and immediate treatment is the administration of adrenaline (epinephrine). Anaphylaxis is a severe, potentially life-threatening allergic reaction that can occur rapidly after exposure to allergens. Symptoms often include difficulty breathing, swelling of the throat or tongue, a rapid drop in blood pressure, and hives.

Injecting adrenaline helps to counteract these reactions by causing the blood vessels to constrict, increasing blood pressure, relaxing the muscles in the airways, and reducing swelling. This response can be life-saving and is considered the first-line treatment in an emergency situation.

While administering an antihistamine might help alleviate some symptoms of allergic reactions, it does not address the life-threatening aspects of anaphylaxis quickly enough. Providing oxygen can be important in supporting breathing but does not treat the underlying cause of anaphylaxis. Encouraging fluid intake may be beneficial in some medical scenarios but is not appropriate as a first response in anaphylaxis, where rapid intervention is needed to stabilize the patient's condition.