Which agent would decrease an allergic reaction primarily related to itching?

The agent that would primarily decrease an allergic reaction related to itching is an antihistamine. Antihistamines work by blocking the action of histamine, a substance in the body that contributes to allergic symptoms. When histamine is released during an allergic reaction, it can lead to symptoms such as itching, swelling, and redness. By inhibiting histamine's effects, antihistamines can significantly alleviate itching and other discomfort associated with allergies.

Antipruritics specifically target the symptom of itching, but they may not address the underlying allergic reaction as effectively as antihistamines. Analgesics are designed to relieve pain, and while they can provide comfort during an allergic reaction if pain is present, they do not specifically combat itching or the allergic response itself. Antibiotics are used to treat bacterial infections and are not effective in managing allergic reactions. Therefore, an antihistamine is the most appropriate choice for reducing itching in the context of an allergic reaction.