What should be administered for an allergic reaction to barbiturates on the lip?

In the case of an allergic reaction to barbiturates, Benadryl is the appropriate medication to administer. Benadryl, or diphenhydramine, is an antihistamine that works by blocking histamine receptors in the body, which helps alleviate symptoms associated with allergic reactions, such as swelling, itching, and redness. These symptoms can occur in localized areas like the lip and may be caused by an allergic response to medications like barbiturates.

Administering Benadryl effectively addresses these symptoms by reducing the body's histamine response, providing relief to the patient. Additionally, Benadryl can help prevent further allergic responses when taken early in the reaction.

Other medications listed, while important in different contexts, are not the first-line treatment for an allergic reaction of this type. Adrenaline is typically reserved for severe anaphylaxis, which may present with more systemic symptoms. Hydrocortisone is a corticosteroid that may be used in severe allergic reactions but is not immediate relief for mild to moderate reactions. Aspirin is an anti-inflammatory and pain reliever but does not address allergic reactions directly.