Which of the following is a second generation H1 blocker?

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

Answer: (A)

Second-generation H1 antihistamines are designed to work mainly outside the brain, with little penetration into the CNS, so they produce fewer sedative effects. Loratadine fits this pattern: it’s a long-acting, non-sedating H1 blocker that has low brain penetration and is transformed into desloratadine, contributing to its prolonged action. In contrast, the other options are first-generation agents that cross the blood–brain barrier readily and cause sedation and anticholinergic effects, even though they can help with allergy symptoms.