This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Histamine, 5-HT and PGs, Subject name: Pharmacology
H1 antihistaminics afford benefit in a number of conditions. All of the following conditions are benefited by antagonism of histamine : 
Select and explain. 
A. Dermographism, B. Insect bite, C. Common cold, D. Seasonal hay fever
C: Common cold
Answer: C: Common cold 
Explanation: In common cold , excessive secretions (like rhinorrhoea) are due to cholinergic overactivity. First generation antihistaminics possess anticholinergic propey and therefore are effective for common cold. On the other hand, all other conditions are allergic and reare benefited by antagonism of H1 receptors.