What is the role of antihistamines in treating upper respiratory conditions?

• A. To stimulate mucus production.
• B. To alleviate inflammation in the lungs.
• C. To block the action of histamine, reducing allergic reactions.
• D. To increase respiratory rate.

Answer: (C)

Antihistamines block histamine from binding to H1 receptors, which dampens the allergic response in the upper airways. When histamine is released during an allergic reaction, it causes sneezing, itching, a runny nose, and watery eyes. By preventing histamine from acting, these drugs lessen those symptoms, making them helpful for allergic rhinitis and related eye symptoms. They don’t treat lung inflammation or directly change the respiratory rate; their main effect is reducing histamine-driven upper-airway symptoms. Some older antihistamines can cause drowsiness, while newer ones are often non-sedating. For congestion, nasal steroids or decongestants may be more effective.