Which of the following is a 2nd generation H1 blocker antihistamine that is Loratadine?

• A. Loratadine
• B. Diphenhydramine
• C. Brompheniramine
• D. Promethazine

Answer: (A)

Second-generation H1 blockers are designed to reduce sedation by limiting entry into the brain. Loratadine fits this profile: it blocks peripheral H1 receptors with minimal penetration into the central nervous system, so it provides allergy relief with little drowsiness.

The other options are first-generation antihistamines; they cross the blood–brain barrier more readily and commonly cause sedation and anticholinergic side effects. Diphenhydramine, brompheniramine, and promethazine are typical examples of this older group.

Therefore, Loratadine is the 2nd generation H1 blocker listed.