What is a common treatment for an acute allergic reaction?

Administering antihistamines is a common treatment for an acute allergic reaction because these medications work by blocking the action of histamine, a substance in the body that causes allergic symptoms. In cases of mild to moderate allergic reactions, antihistamines can relieve symptoms such as itching, hives, and nasal congestion effectively.

For severe allergic reactions, such as anaphylaxis, while antihistamines may still be used, they are typically not the first line of treatment; epinephrine is preferred. Nevertheless, antihistamines are significant in managing subsequent symptoms after the immediate threat has been addressed.

The other options do not specifically address the treatment of an acute allergic reaction. Performing CPR is relevant in cases of cardiac arrest or severe respiratory distress but not directly applicable to allergic reactions unless they lead to those outcomes. Providing oxygen therapy may be beneficial for someone experiencing respiratory distress, but it's not a treatment for the immediate allergic reaction itself. Encouraging fluid intake can help maintain hydration but doesn't treat the allergic symptoms directly.