Naloxone—also known by brand names such as Narcan and Kloxxado—can be a lifesaving medication when used promptly in cases of opioid overdose.¹ If you or someone you care about takes prescription opioid medication or uses illicit opioids such as heroin, you may wish to learn more about naloxone, as well as rehab for opioid use disorder (OUD). Keep reading to learn about how naloxone works to reverse an opioid overdose, as well as dosing information and how to find addiction treatment.

What Is Naloxone Used For?

Naloxone is a medication that can rapidly reverse an opioid overdose.¹ Naloxone is an opioid agonist that attaches to opioid receptors in the brain and reverses and blocks the effects of other opioids.¹ It can restore slowed or stopped breathing in a person who’s overdosed on prescription opioids (e.g. oxycodone/Oxycontin, hydrocodone, fentanyl, morphine), heroin, and illicitly manufactured fentanyl. Naloxone has no effect on a person who does not have opioids in their system, and it is not a medication or treatment for OUD.¹ Naloxone can be injected into muscle, under the skin, or into the veins. It can also be given as a nasal spray.²

Injectable naloxone typically requires training on how to properly draw the liquid into a syringe and administer it.^1,3,4,5 The FDA has recently approved a single-dose prefilled syringe known as Zimi.¹ A handheld naloxone auto-injector known by the brand name Evzio (as well as a generic equivalent) was once available but was discontinued in 2020.

Sometimes injectable naloxone is packaged with an atomizer, allowing it to be sprayed into the nose. It is sometimes found this way in emergency opioid overdose kits; however, these are not FDA-approved. Prepackaged, FDA-approved nasal spray devices (both generic and branded as Narcan and Kloxxado) require no assembly, and a study in 2019 found that they deliver higher blood levels of naloxone than improvised nasal spray devices.¹

Are There Any Side Effects of Naloxone?

Naloxone is a safe medicine and side effects are rare. It has no effect on a person who does not have opioids in their system. Like with any medication, however, people might have allergic reactions to it, such as hives or swelling in the face, throat, or lips.

When to Use Naloxone

Narcan is used to restore breathing in someone who has stopped breathing or experiences slowed breathing due to opioid overdose.¹ An opioid overdose can be life-threatening. It is a medical emergency that can cause death, which is why it’s crucial to administer naloxone to someone as soon as possible if you suspect that they have overdosed.⁶ Naloxone can save a person’s life when used in time.³It can be safely administered to prevent overdose-related injury and death not only by medical professionals or public safety officers (EMS, fire, and police), but also by laypeople who witness an overdose.⁷

People who take prescription opioids or use illicit opioids, as well as their friends and family members, should be aware of the signs of opioid overdose so that they can take action in the event of an overdose.⁸ The three key symptoms to look for—referred to as the “opioid overdose triad”—are:⁹

Small, pinpoint pupils.
Difficulty breathing (i.e. breathing that is slowed, shallow, or stopped).
Loss of consciousness/unconsciousness.

People should call 9-1-1 and seek immediate medical assistance after receiving naloxone.¹ This is because the effects of naloxone start to subside after 30–90 minutes.¹ Opioids can remain in your system for longer than this, so you could still experience overdose effects after naloxone wears off, and stronger opioids like fentanyl might require multiple doses of naloxone.¹ People who have received naloxone should be monitored constantly until emergency assistance arrives, and their breathing should be closely monitored for another 2 hours.¹

Availability of Naloxone

Healthcare providers, governmental bodies, and communities have undertaken a number of initiatives to help make naloxone more available to people who need it.^10,11 All 50 states and the District of Columbia have enacted a naloxone access law of some kind. The authority and protection afforded by these laws varies across the country, although many states allow people to obtain naloxone from pharmacists without prescriptions.^4,6

The FDA has required manufacturers of all opioid pain relievers and medicines that treat OUD to add new recommendations about naloxone to the prescribing information.⁶ They advise people who use opioid painkillers to discuss the availability of naloxone with their physicians.⁶ The FDA recommends that physicians also discuss the risk of opioid overdose and the uses of naloxone with patients who are prescribed opioids.⁶ Additionally, they ask that physicians consider co-prescribing naloxone to people who are deemed to have an increased risk of opioid overdose, as well as to those who have been prescribed medications to treat OUD.⁶

Who Can Receive Naloxone?

Naloxone is an essential medication for individuals, families, first responders, and communities to help reduce opioid overdose deaths. You can discuss whether naloxone is appropriate for you or a loved one with your physician. People who may be candidates for naloxone include:^4,6,12

Those who take prescription opioids for pain management, especially those who take high doses of opioids or use alcohol or other sedatives, like benzodiazepines.
People on rotating opioid medication regimens.
People who abuse prescription opioids or who use heroin or other illicit synthetic opioids.
People with OUD, especially those who have completed opioid detox or treatment that does not include maintenance with methadone, buprenorphine, or naltrexone.
Those who have been recently discharged from emergency medical care following an opioid overdose.
People who have recently been released from prison and have a history of opioid abuse/OUD.

Additionally, the American College of Obstetricians and Gynecologists has advised that, although naloxone might contribute to fetal stress, naloxone is recommended for pregnant women in the case of overdose to help save the woman’s life.¹³ The Centers for Disease Control and Prevention (CDC) says that pregnant women can safely be administered low doses of naloxone under physician supervision.¹²

It’s important to remember that naloxone is only effective for opioid overdose, so it won’t reverse overdose on other nonopioid drugs.^12,14 If someone displays signs of opioid overdose but it’s not clear whether their symptoms are caused by opioids, naloxone should be administered. Naloxone is effective for overdoses on opioids whether or not they are used in combination with other sedatives or stimulants, and naloxone will not cause harm if the person hasn’t used opioids.^12,14

Naloxone Dosages

One dose of naloxone typically reverses an opioid overdose for around 30–90 minutes.¹ It’s possible that a person can feel the effects of opioid overdose return after the naloxone wears off.¹ Some people may require more than one dose, depending on the type of opioid they used, but this decision should be made and administered by appropriate medical personnel when possible.^1,15 People who regularly take opioids may have withdrawal symptoms after being given naloxone. These symptoms are not usually life-threatening and include anxiety or agitation, rapid heart rate, sweating, nausea, vomiting, tremors, and changes in blood pressure.¹

Safety Measures

Laypersons who administer naloxone should always call 9-1-1 for emergency medical services after doing so, even if the person’s breathing is restored. People need immediate medical care after receiving naloxone and may require additional care.¹

Regardless of the form of naloxone you use, you should receive training and understand how to use it.¹ In most states, people who are at risk of opioid overdose and their friends and families can receive training on naloxone administration.¹ Individuals who receive prescriptions for injectable naloxone/Narcan injections can receive instructions on how to use the substances from their doctors or pharmacists.¹²

How to Administer Naloxone

The discontinued auto-injector is administered into the front side of the thigh.³ The prepackaged nasal spray is designed to be sprayed into one nostril while the person lies on their back.¹Improvised nasal devices in emergency opioid overdose kits usually come with instructions describing proper delivery.

You should check the expiration date and read the product instructions before using naloxone.¹ Naloxone should be stored at room temperature and should be replaced if exposed to temperatures below 39°F or above 104°F.¹²

If you are in a position to administer naloxone, you should first check for a suspected overdose.¹⁵ It is recommended that you shout “wake up” and check the person’s breathing. If they do not wake up immediately, you can give the first dose.^15,^16,17Then call 9-1-1 immediately.^14,15 Wait 2–3 minutes. If they don’t wake up, you can administer another dose, and then continue to administer doses every 2–3 minutes until the person wakes up.^15,16 Remain with the person until emergency medical assistance arrives.^15,16

Naloxone Drug Interactions

Different drugs and medications may interact with naloxone.¹⁷ This includes cold or cough medicines and antidiarrheal medicines.¹⁷ You should discuss your use of prescription or over-the-counter medications and any potential interactions with your doctor or pharmacist.¹⁷In the event of overdose, a pharmacist, doctor, or other qualified medical professional should help to determine the appropriate dosage of naloxone for the person overdosing and check for any potential drug/medication interactions. Remember that it’s essential to obtain immediate medical care in the case of an opioid overdose.

Opioid Treatment Types

If you or someone you care about is struggling with opioid addiction, you should know that proper treatment can help you refrain from substance use and take back control of your life. Different treatments—including inpatient or outpatient care, behavioral therapy, counseling, and medications—can help people recover from OUD.⁴

Medications such as buprenorphine (Suboxone, Subutex), methadone, and naltrexone (Vivitrol) are FDA-approved for the treatment of OUD and can help you stay sober.¹⁸

Find Opioid Addiction Treatment Programs

If you or a loved one is struggling with opioid addiction, help is available and recovery is possible. Rehab programs are located throughout the U.S., and many offer specialized treatment that can cater to individual needs. You can use SAMHSA’s Find Treatment tool to search for facilities. Many state government websites will provide local drug and alcohol resources to those in need. To find your state government’s website, do a web search for your state name and ‘.gov.’

American Addiction Centers (AAC) is a leading treatment provider and has trusted rehab programs across the country. Please contact us free at for helpful advice, information, and admissions. You can also call free drug abuse helpline numbers.

Locate an AAC drug and alcohol rehab center using the drugabuse.com directory and instantly verify your insurance coverage so that you can get started on the path to recovery today.

Understanding Naloxone and Narcan