What condition does Narcan effectively reverse?

Narcan, also known as naloxone, is an opioid antagonist that specifically reverses the effects of opioid overdose. In cases of opioid overdose, the respiratory system can become severely depressed, leading to inadequate oxygen supply and potentially fatal consequences. Narcan works by binding to the same receptors in the brain that opioids target, effectively displacing them and reversing their sedative effects. This allows normal respiratory function to resume and can be a lifesaving intervention.

The other conditions listed do not respond to Narcan. Alcohol overdose is managed differently, generally requiring supportive care and monitoring. Stimulant overdoses, like those from cocaine or methamphetamine, lead to increased heart rate and agitation, not suppressed breathing, which naloxone does not address. Anxiety attacks, while distressing, are not treated with naloxone as they do not involve opioid receptors. Thus, the effectiveness of Narcan is specifically tied to its action against opioids, making it the correct answer in this context.