Short answer: Naloxone is an emergency medicine that reverses opioid overdose by knocking opioids off their receptors. Narcan and RiVive nasal sprays have been sold over the counter since 2023, without a prescription. It is safe to give to anyone who may be overdosing and has no effect on people who have not taken opioids.
Key takeaways
- What it is: Naloxone is an opioid antagonist (overdose reversal) and not a federally controlled substance.
- Main uses: Emergency treatment of opioid overdose.
- Timing: effects start in 2 to 3 minutes and last 30 to 90 minutes.
- Most dangerous mix: Opioids (fentanyl, heroin, oxycodone, methadone), which can cause reverses sedation and slowed breathing; can cause sudden withdrawal.
- Naloxone: this is the reversal medicine for opioid overdose.
- Dependence risk: None.
- Legal route: sold without a prescription; follow the Drug Facts label.
What is naloxone?
Naloxone reverses an opioid overdose, including from fentanyl, heroin, prescription opioids, and nitazenes. It restores breathing within minutes by blocking opioid receptors.
In March 2023 the FDA approved Narcan 4 mg nasal spray for sale without a prescription, followed by RiVive 3 mg in July 2023. The CDC and FDA recommend that anyone who uses opioids, lives with someone who does, or takes high-dose prescription opioids keep naloxone at hand.
Quick facts
| Fact | Naloxone |
|---|---|
| Generic name | Naloxone hydrochloride |
| Brand names | Narcan and RiVive (over the counter); Kloxxado, Zimhi, generic injection (prescription) |
| Drug class | Opioid antagonist |
| US legal status | Not controlled; nasal sprays sold over the counter since 2023 |
| Approved uses | Emergency treatment of known or suspected opioid overdose |
| Forms | Nasal spray (3 mg, 4 mg, 8 mg); injection; autoinjector |
| Onset | 2 to 3 minutes |
| Duration | 30 to 90 minutes, often shorter than the opioid |
| Related medicine | Nalmefene (Opvee nasal spray, Zurnai autoinjector) |
How long does naloxone last?
- Starts working: 2 to 3 minutes
- Effects last: 30 to 90 minutes
Timing varies with the dose, the form, how it is taken, liver and kidney function, age, and other drugs taken at the same time.
What are the biggest risks of naloxone?
Sudden withdrawal: in people dependent on opioids, naloxone can trigger abrupt withdrawal: vomiting, sweating, shaking, agitation, fast heartbeat, and body aches. It is unpleasant but rarely dangerous, and much safer than an untreated overdose.
Overdose can return: naloxone often wears off before long-acting opioids, fentanyl analogs, or extended-release pills, so the person can stop breathing again. Always call 911 and stay with them.
Rare effects: fluid in the lungs and abnormal heart rhythms have been reported, mainly after surgery or in people with heart disease.
What should you never mix with naloxone?
| Combined with | What happens | What to know |
|---|---|---|
| Opioids (fentanyl, heroin, oxycodone, methadone) | Reverses sedation and slowed breathing; can cause sudden withdrawal | Intended use; call 911 and monitor |
| Buprenorphine | Partly blocked; larger or repeated doses may be needed | Keep giving doses and call 911 |
| Xylazine or medetomidine mixed with opioids | Restores breathing but sedation can persist | Give naloxone for breathing; support the person |
| Naltrexone | Both block opioid receptors | No harmful interaction |
Check any combination with the DoseUses combination checker or ask a pharmacist.
What are the signs of a naloxone overdose, and what should you do?
A person who responds to naloxone usually starts breathing normally within 2 to 3 minutes and may wake up suddenly, confused, or in withdrawal. Naloxone itself has a very low risk of serious harm, even at high doses.
If someone may have overdosed
- Call 911 if the person is unresponsive, cannot be woken, has blue or gray lips, or is breathing slowly or not at all.
- Give naloxone (Narcan or a generic nasal spray, sold without a prescription) into one nostril. If there is no response after 2 to 3 minutes, give another dose.
- If you are trained, give rescue breaths. Otherwise place the person on their side so they do not choke.
- Stay with them. Naloxone can wear off before naloxone does, so the overdose can return even after the person wakes up.
- Most states have Good Samaritan laws that protect people who call 911 for an overdose from some drug charges.
Can naloxone cause withdrawal?
Naloxone is not addictive and does not cause dependence. It can, however, trigger sudden opioid withdrawal in someone who is physically dependent on opioids.
- MinutesRapid onsetVomiting, sweating, shaking, goosebumps, yawning, runny nose, agitation, and fast heartbeat.
- 30 to 90 minutesNaloxone wears offWithdrawal eases, but sedation and slowed breathing can return if opioids are still in the body.
- HoursMonitoring periodStay with the person. Do not let them take more opioids to relieve withdrawal, which can cause a second overdose.
See the withdrawal timelines and the full naloxone withdrawal guide.
Is naloxone legal?
Naloxone nasal spray does not need a prescription in the United States. Narcan and RiVive are sold over the counter at pharmacies, grocery and convenience stores, vending machines, and online.
- Cost: a two-pack of Narcan usually costs about $45 at retail. Many health departments, harm reduction programs, libraries, and schools hand it out free.
- Insurance: prescription naloxone, including generics and Kloxxado, is covered by most insurance and Medicaid plans when written by a clinician or under a pharmacy standing order.
- Good Samaritan laws: every state and Washington, DC, has a law protecting people who give naloxone in good faith from civil liability.
Outside the United States
| Country | Status |
|---|---|
| United Kingdom | Prescription-only medicine, but drug services can supply it to anyone without a prescription |
| Canada | Nasal naloxone available without a prescription; free through provincial take-home programs |
| Australia | Free without a prescription under the national Take Home Naloxone program |
| International | Not under UN control; on the WHO Model List of Essential Medicines |
Frequently asked questions about naloxone
Can naloxone hurt someone who is not overdosing on opioids?
No. It has no effect on people without opioids in their system, so it is safe to give whenever an opioid overdose is possible.
How many doses of naloxone might be needed?
Often one, but fentanyl, carfentanil, and nitazene overdoses sometimes need two or more. Give a new dose every 2 to 3 minutes if there is no response.
Does naloxone expire?
Yes, but the FDA has extended Narcan's shelf life to 4 years. Expired naloxone may still help if nothing else is available.
Do I need a prescription for Narcan?
No. Narcan and RiVive nasal sprays are sold over the counter in the US.
What is the difference between naloxone and nalmefene?
Both reverse opioid overdose. Nalmefene (Opvee, Zurnai) lasts longer but is more likely to cause prolonged withdrawal.
Sources
- Narcan (naloxone) prescription information, DailyMed, US National Library of Medicine.
- Information about naloxone and nalmefene, US Food and Drug Administration.
- FDA approves first over-the-counter naloxone nasal spray, US Food and Drug Administration, March 2023.
- BeSafeRx: Your Source for Online Pharmacy Information, US Food and Drug Administration.
- International drug control conventions, United Nations Office on Drugs and Crime.
This guide summarizes the sourced DoseUses Naloxone profile, written from FDA labels, DEA rules, and federal health agencies. It is educational and is not medical advice. Last updated October 5, 2026.
