Which of the following is a potential adverse effect of naloxone administration?

• A. Hypotension
• B. Bradycardia
• C. Tachycardia
• D. Hypoglycemia

Answer: (C)

Naloxone works by blocking opioid receptors to rapidly reverse opioid-induced respiratory depression and sedation. In people who are opioid-dependent, this sudden reversal can precipitate withdrawal, which triggers a surge of sympathetic activity. That surge commonly causes tachycardia as the heart rate rises in response to increased catecholamines and agitation. So tachycardia is the expected adverse effect when naloxone precipitates withdrawal or when it’s given in dose ranges that provoke a strong reversal.

Hypotension isn’t typically caused by naloxone itself and, in many cases, reversal can actually be accompanied by higher blood pressure rather than low. Bradycardia would be inconsistent with withdrawal-related sympathetic activation. Hypoglycemia is not a known direct effect of naloxone.