Does tolerance develop to opioid-induced sedation?

• A. No
• B. Sometimes
• C. It depends on the opioid
• D. Yes

Answer: (D)

Tolerance to opioid-induced sedation is common with continued opioid use. When opioids bind to μ-opioid receptors over time, the brain adapts—receptor desensitization and downregulation occur, and downstream signaling pathways (like changes in cAMP activity) adjust. These neuroadaptive changes make the usual dose produce less sedative effect, so patients often require higher doses to achieve the same level of drowsiness. The extent of this tolerance can vary by specific opioid and by individual factors, and safety remains a concern: even with tolerance, there can still be significant risk of respiratory depression, especially in elderly patients or when other central nervous system depressants are involved.