Naloxone is an opioid antagonist medication used to rapidly reverse an opioid overdose, including overdoses involving heroin, fentanyl, and prescription pain medications like oxycodone, hydrocodone, and morphine.(Source) It works by quickly binding to opioid receptors in the brain and blocking the effects of opioids, which can restore normal breathing in a person whose breathing has slowed or stopped due to an overdose.(Source)

During an opioid overdose, the central nervous system and respiratory system are severely depressed. The person may become extremely drowsy, lose consciousness, and stop breathing adequately. Without fast intervention, this lack of oxygen can lead to brain injury or death within minutes.(Source)

Naloxone is a harm‑reduction medication. It is not a treatment for addiction itself, but it can keep someone alive long enough to receive emergency care and, ultimately, enter evidence‑based addiction treatment.