This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Opioids, Subject name: Pharmacology
Tolerance occurs to all side effects of Morphine, EXCEPT 
Select and explain. 
A. Sedation, B. Constipation, C. Pain relieving, D. Euphoric effect
B: Constipation
Answer: B: Constipation 
Explanation: Ans. is 'b' i.e., Constipation High degree of tolerance develops to morphine and related opioids if the drug is used repeatedly.Tolerance develops to all the actions except constipating and miotic action.