Which statement best describes tolerance development for opioid-induced nausea?

• A. Tolerance does not develop
• B. Tolerance develops only at high doses
• C. Tolerance does develop
• D. Tolerance is immediate

Answer: (C)

Nausea from opioids typically diminishes with continued use because the nervous system adapts to the emetogenic effects. At first, mu receptor activation in the chemoreceptor trigger zone and vestibular pathways triggers nausea. With ongoing exposure, receptor signaling and downstream pathways become less responsive, leading to a reduced emetic response. This means tolerance to opioid-induced nausea does develop over days to a week or so, though it can vary and some individuals may still experience nausea. The statement that nausea tolerance does not develop or that it’s only at high doses or immediate is not consistent with how the body adapts to opioids.