Which of the following should be administered during an anaphylactic reaction?

During an anaphylactic reaction, the administration of adrenaline (often referred to as epinephrine) is critical due to its life-saving properties. Adrenaline works by constricting blood vessels, which counteracts the severe drop in blood pressure that can occur during anaphylaxis. It also opens the airways, leading to improved breathing, and can reduce swelling and hives.

In addition to adrenaline, administering oxygen is essential to support respiration, especially if the patient is experiencing breathing difficulties or low oxygen saturation levels. The use of a syringe for precise dosing of adrenaline ensures that the patient receives the correct amount for effective treatment.

Other options, while they may provide some support, do not address the immediate and potentially life-threatening symptoms of anaphylaxis effectively. For instance, antihistamines can help alleviate symptoms but are not rapid-acting and are not sufficient as a first-line treatment in this critical situation.