This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
H1 blockers are useful as: March 2013 
Select and explain. 
A. Antacids, B. Anti-allergic, C. Anti-asthmatics, D. Anti-migraine
B: Anti-allergic
Answer: B: Anti-allergic 
Explanation: Ans. B i.e. Anti-allergic H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions.