Which long-acting antihistamine is considered sedating?

• A. Loratadine
• B. Azelastine
• C. Fexofenadine
• D. Cetirizine

Answer: (D)

Sedation potential among long-acting antihistamines varies because of how well the drug enters the central nervous system. Cetirizine is more likely to cause mild drowsiness than the other long-acting options listed because it crosses the blood-brain barrier to a greater extent. Loratadine and fexofenadine are designed to be non-sedating with limited CNS penetration, so they are less likely to cause drowsiness. Azelastine is typically used as a nasal spray with less systemic exposure, so sedation is not its defining trait. Therefore, cetirizine is the sedating long-acting option.