In case of severe allergic reaction, what should you administer?

In the case of a severe allergic reaction, commonly referred to as anaphylaxis, the immediate treatment is the administration of an epinephrine auto-injector if one is available. Epinephrine is a life-saving medication that rapidly counteracts the symptoms of anaphylaxis by narrowing blood vessels, leading to an increase in blood pressure, and opening the airways, which alleviates difficulty in breathing. It also reduces swelling and hives, addressing multiple life-threatening features of anaphylaxis.

While antihistamines may help alleviate some symptoms of less severe allergic reactions, they do not address the critical and potentially life-threatening symptoms of anaphylaxis, such as airway constriction and significant drops in blood pressure. Oxygen can be helpful in cases of respiratory distress but is not a primary treatment for anaphylaxis. Saline solution does not treat the underlying issues of severe allergic reactions and is generally used for hydration or other medical purposes, but not for addressing anaphylaxis. Thus, the correct course of action in severe allergic reactions is to use an epinephrine auto-injector, as it is the most effective and immediate treatment available.