What Is Narcan? How Naloxone Reverses an Opioid Overdose

Medically reviewed
Written by Still Detox Editorial Team
Updated September 25, 2026

Narcan is the brand name of a naloxone nasal spray, a medicine that quickly reverses an opioid overdose by blocking opioids in the brain and letting a person breathe again. You can buy Narcan without a prescription.

Knowing how to use it, what it cannot do and where to get it free can help you act fast when someone will not wake up.

What does Narcan do?

Narcan reverses an opioid overdose by pushing opioids off the brain's opioid receptors, which lets slowed or stopped breathing start again. Naloxone can restore normal breathing within 2 to 3 minutes, according to the CDC.

How does naloxone reverse an overdose?

Naloxone is an opioid antagonist. Naloxone attaches to opioid receptors in the brain and blocks the effects of other opioids while the medicine is active.

What does Narcan do to someone who has not taken opioids?

Narcan has no effect on someone who has no opioids in their system. Naloxone is not a controlled substance and has no abuse potential.

How do you use Narcan?

You use Narcan by spraying one dose into either nostril, calling 911 right away, and giving another dose every 2 to 3 minutes if the person does not wake up. The steps below follow the FDA-approved Drug Facts label on the Narcan box.

Three steps for giving Narcan nasal spray: spray one dose, call 911, and repeat every 2 to 3 minutes

There are 5 steps to giving Narcan:

Check for an overdose: A person in overdose will not wake up, is very sleepy or is not breathing well.
Give the first dose: Insert the nozzle into either nostril and press the plunger firmly.
Call 911: Call 911 immediately after giving the first dose.
Wait and repeat: Wait 2 to 3 minutes, then give another dose every 2 to 3 minutes until the person wakes up.
Stay with the person: Stay until the ambulance arrives, even if the person wakes up, and give another dose if they become very sleepy again.

"Give the first dose, then make the call. Narcan buys time, and the ambulance crew needs to be on the way before the medicine wears off."

Britney Marshall, RN, Director of Nursing, Still Detox

What are the signs of an opioid overdose?

An opioid overdose usually looks like a person who cannot be woken, with slow or noisy breathing, tiny pupils and discolored lips or nails. You give naloxone based on these signs, without needing to know which drug the person took.

Watch for these 4 common signs:

Unresponsiveness: The person will not wake up or is very sleepy.
Breathing changes: Breathing is slow, shallow or difficult, with choking sounds or a gurgling or snoring noise.
Pinpoint pupils: The pupils are small and do not react to light.
Discolored skin: The skin looks discolored, especially the nails or lips.

Many people try to spot fentanyl by what fentanyl smells like, but the safer rule is to give naloxone for any suspected overdose, whatever the drug.

How long does Narcan last?

Narcan works for only 30 to 90 minutes, and many opioids stay in the body longer than that, so an overdose can come back after the person wakes up. The CDC advises staying with the person until help arrives, or for at least four hours.

Why can an overdose come back after Narcan?

An overdose comes back when naloxone wears off while opioids are still active in the body. Signs of a returning overdose, such as heavy sleepiness or slow breathing, mean the person needs another dose and emergency care.

Why does fentanyl need more than one dose?

Fentanyl is a stronger opioid, and more than one dose of naloxone may be needed when fentanyl is involved. Keep giving doses every 2 to 3 minutes until the person wakes up or the ambulance arrives.

What will Narcan not reverse?

Narcan only works on opioids, so naloxone will not reverse an overdose caused only by cocaine, methamphetamine or xylazine (tranq). Because you often cannot know what someone took, give naloxone for any suspected overdose.

Drugs naloxone will not reverse, including stimulants, xylazine (tranq) and non-opioid sedatives

There are 3 situations where Narcan will not fully wake someone:

Stimulants: Naloxone will not reverse an overdose from cocaine or methamphetamine on its own.
Xylazine (tranq): Naloxone does not reverse xylazine, a non-opioid sedative, so a person may stay drowsy after the opioid is reversed.
Non-opioid sedatives: Naloxone has no effect on a person with no opioids in their system, so it cannot undo a sedative taken without opioids.

That limit matters for benzodiazepines, the drug class behind common questions such as can you take Xanax and Valium together.

What happens after someone gets Narcan?

After Narcan, a person who is physically dependent on opioids may go into withdrawal within minutes, with sweating, nausea, vomiting and a racing heart. Naloxone ends the emergency, but it is not a treatment for opioid use disorder (OUD).

What to expect after Narcan: opioid withdrawal, a returning overdose, the 30 to 90 minute window and where to get help

Withdrawal after naloxone can also bring headaches and changes in blood pressure. The opioid withdrawal timeline shows what those first days usually look like.

Once the emergency is over, the next step can be opioid addiction treatment in Boca Raton, where medical detox manages withdrawal with 24/7 nursing and an in-person evaluation by the Medical Director within 24 hours of arrival.

Does Narcan expire?

Narcan does expire, and you should follow the expiration date printed on the package. The FDA extended the shelf life of newly made Narcan 4 mg nasal spray from 3 years to 4 years, so check the date on your box.

Is expired Narcan better than nothing?

An in-date kit is the one to rely on, so replace Narcan once it expires, because the FDA advises following the printed date. In any overdose, call 911 right away so responders can bring more naloxone.

Can you keep Narcan in your car?

Narcan needs to stay between 36 and 77 degrees Fahrenheit and away from heat above 104 degrees Fahrenheit. A parked car can get hotter than that in summer, so a bag you carry is often a safer place for it.

How much does Narcan cost, and where can you get it free?

Narcan's price depends on where you buy it, how you get it and which product you choose, and many community programs give naloxone out free. Since the 2023 over-the-counter approval, Narcan can be sold in places like drug stores, grocery stores, convenience stores and gas stations.

How do you get free Narcan in Florida?

Florida residents can get free naloxone kits through iSaveFL, which makes kits available across the state and helps people find naloxone in their community.

How do you get free Narcan in New Jersey?

New Jersey's Naloxone365 program lets you request naloxone for free at participating pharmacies, with no prescription and no need to give a name or reason. Each visit provides one two-dose nasal spray kit.

Does insurance cover Narcan?

Insurance coverage for Narcan depends on your plan. If you have insurance, ask your insurer or pharmacist about the cost, and if you do not, compare prices at local pharmacies or use a free program.

Will you get in trouble for calling 911 about an overdose?

Florida and New Jersey both have Good Samaritan laws that protect a person who calls for help during an overdose from arrest and prosecution for certain drug offenses. Both states also extend protection to the person who had the overdose.

What does Florida's Good Samaritan law cover?

Under Florida Statute 893.21, a person who seeks medical help in good faith for an alcohol or drug overdose may not be arrested, charged, prosecuted or penalized for certain drug offenses, such as possession, when the evidence was found because they called for help. The law also covers the person who had the overdose and needed medical help.

What does New Jersey's Overdose Prevention Act cover?

New Jersey's Overdose Prevention Act says a person who seeks medical help in good faith for someone having a drug overdose shall not be arrested, charged, prosecuted or convicted for certain drug offenses, such as possession or use. The act also covers the person who had the overdose, and it protects anyone who gives naloxone in line with the act from criminal or civil liability.

This section summarizes the laws and is not legal advice.

Where can you get help for opioid addiction after an overdose?

Medical detox followed by residential treatment is one next step after an overdose, because naloxone treats the emergency and not the opioid use disorder. Still Detox offers both levels of care in Boca Raton, Florida and Mays Landing, New Jersey.

There are 4 parts to opioid detox at Still Detox:

Medical evaluation: The Medical Director evaluates every client in person within 24 hours of arrival.
Monitored withdrawal: Staff check vital signs every 4 hours, with 24/7 nursing through detox.
Detox length: Detox averages 7 to 10 days and runs up to 14 days for complex cases.
Residential care: Most clients step down to residential treatment around day 8, for a program of up to 30 days.

If you live in South Jersey, Philadelphia or Delaware, the Mays Landing facility provides the same detox and residential care through opioid rehab and detox in Atlantic County, New Jersey, about 26 minutes from Atlantic City.

What else do people ask about Narcan?

Is Narcan addictive?

Narcan is not addictive. Naloxone has no abuse potential, which is why naloxone is not a controlled substance.

Do you need a prescription for Narcan?

You do not need a prescription for Narcan 4 mg nasal spray. Naloxone is available over the counter in all 50 states.

How many doses are in a Narcan box?

Each Narcan nasal spray device holds one dose and sprays one time only. Because a repeat dose may be needed, keep more than one device on hand.

How fast does Narcan work?

Narcan usually restores normal breathing within 2 to 3 minutes. If the person does not respond, give another dose every 2 to 3 minutes.

Can you give Narcan to yourself?

You cannot give Narcan to yourself during an overdose. Tell the people around you that you carry naloxone and where you keep it, so they can use it on you.

Sources

Centers for Disease Control and Prevention. (2025, June 11). Lifesaving naloxone. cdc.gov
Centers for Disease Control and Prevention. (2024, May 2). 5 things to know about naloxone. cdc.gov
Centers for Disease Control and Prevention. (2024, May 16). What you should know about xylazine. cdc.gov
Emergent Devices Inc. (2026). NARCAN (naloxone HCl) nasal spray 4 mg: Drug Facts carton labeling. U.S. Food and Drug Administration. fda.gov
National Institute on Drug Abuse. (2022, January 11). Naloxone DrugFacts. nida.nih.gov
U.S. Food and Drug Administration. (2023, March 29). FDA approves first over-the-counter naloxone nasal spray. fda.gov
U.S. Food and Drug Administration. (2024, January 17). FDA announces shelf-life extension for naloxone nasal spray. fda.gov
Fla. Stat. § 893.21 (2025). Alcohol-related or drug-related overdoses; medical assistance; immunity from arrest, charge, prosecution, and penalization. flsenate.gov
Overdose Prevention Act, P.L. 2013, c. 46 (2013). New Jersey Legislature. njleg.gov
New Jersey Department of Human Services. (2023, August 7). Human Services Commissioner announces launch of StopOverdoses website detailing pharmacies offering free & anonymous overdose antidote. nj.gov
iSaveFL. (n.d.). I Save Florida. isavefl.com

Written by

Still Detox Editorial Team

Still Detox

The Still Detox Editorial Team writes and updates these articles for Still Detox, a Joint Commission accredited drug and alcohol detox and residential treatment provider with facilities in Boca Raton, Florida, and Mays Landing, New Jersey.

Medically reviewed by

Dr. Gladys Martinez

Medical Director, Still Detox

Dr. Gladys Martinez is the Medical Director at Still Detox and oversees all medical care. Dr. Martinez evaluates every client in person within 24 hours of admission and oversees detox medication tapers. Read Dr. Gladys Martinez’s full bio.

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What Is Narcan? How Naloxone Reverses an Opioid Overdose