Which of the following describes a first-line antihistamine regimen for allergic rhinitis in adults?

• A. Diphenhydramine
• B. Long-Acting, Sedating
• C. Chlorpheniramine
• D. Once-Daily, Nonsedating

Answer: (D)

The key idea is choosing an antihistamine that effectively relieves allergic rhinitis symptoms with minimal sedation and convenient dosing. For adults, the preferred first-line option are second-generation antihistamines that are nonsedating and typically taken once daily. These drugs work well to reduce sneezing, itching, and rhinorrhea, but they cross the blood-brain barrier far less than older agents, so they cause little to no drowsiness and fewer cognitive side effects. The once-daily dosing also helps with adherence, making it easier to maintain symptom control over time.

Diphenhydramine and chlorpheniramine are older, first-generation antihistamines that enter the brain easily and cause noticeable sedation and anticholinergic effects, which is why they’re not favored as first-line choices. A descriptor like long-acting, sedating is inconsistent with the goal of a non-sedating, once-daily regimen. The option that emphasizes once-daily and nonsedating fits the best approach to initial management.