**Naloxone (Narcan) reverses opioid overdose by rapidly binding to opioid receptors—especially the μ-receptors that suppress breathing—and displacing opioids such as heroin, fentanyl, oxycodone, or morphine.** It can restore breathing within a few minutes. It does not reverse overdoses from non-opioid drugs, though it generally will not harm someone if opioids are not involved.
### When a bystander should use it
Give naloxone immediately if an opioid overdose is possible and the person:
- Cannot be awakened or is unusually unresponsive
- Is breathing very slowly, irregularly, or not at all
- Has blue/gray lips or fingertips
- Has pinpoint pupils
- Makes choking, gurgling, or unusual snoring sounds
If unsure, **use it—do not wait for certainty.**
### What to do
1. **Call emergency services immediately.**
2. Give naloxone according to the device instructions—commonly one nasal spray into one nostril.
3. Start rescue breathing or CPR if the person is not breathing normally; use an AED if available.
4. If there is no response after **2–3 minutes**, give another dose, alternating nostrils. Potent opioids such as fentanyl may require several doses.
5. Once breathing, place the person on their side and stay with them.
Naloxone’s effect is temporary—often **30–90 minutes**—while opioids may last longer, so the person can stop breathing again and still needs emergency medical care. Sudden withdrawal, including vomiting or agitation, can occur after naloxone.