Opioids suppress breathing, leading to which condition?

• A. Respiratory depression
• B. Bronchospasm
• C. Tachypnea
• D. Apnea

Answer: (A)

Opioids blunt the brain’s control of breathing. They bind to mu-opioid receptors in the brainstem, which slows the respiratory center’s activity and raises the level of CO2 the body tolerates before triggering a deeper breath. This reduces both the rate and depth of breathing, a state called respiratory depression. Over time, ventilation becomes insufficient to meet the body's oxygen needs, and carbon dioxide builds up, which can lead to hypoxia and acidosis.

Bronchospasm would involve narrowing of the airways themselves, which opioids don’t typically cause as the primary effect. Tachypnea is rapid breathing, the opposite of what opioids do when they depress drive to breathe. Apnea means complete cessation of breathing; while severe overdose can progress to apnea, the general and most direct consequence of opioid action on the respiratory center is respiratory depression—reduced breathing effort and ventilation.