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Narcan (injection)

Generic name: naloxone (injection) [ nah-LOX-one ]
Brand names: Narcan, Zimhi
Drug class: Antidotes

Medically reviewed by Drugs.com on Aug 4, 2023. Written by Cerner Multum.

What is naloxone?

Naloxone is used in an emergency situation to treat a known or suspected opioid overdose in an adult or child.

This medicine should not be used in place of emergency medical care for an overdose.

Naloxone may also be used for purposes not listed in this medication guide.

Naloxone side effects

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Because naloxone reverses opioid effects, this medicine may cause sudden withdrawal symptoms such as:

Sudden withdrawal symptoms in a baby younger than 4 weeks old may be life-threatening if not treated the right way. Symptoms include unusual crying, stiffness, overactive reflexes, and seizures. Call your doctor or get emergency medical help if you are not sure how to properly give this medicine to a baby.

Common side effects of Narcan may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Narcan side effects (more detail)

Warnings

Naloxone is used to reverse the effects of opioid medicine and treat an opioid overdose. An opioid overdose can be fatal. Symptoms may include severe drowsiness, pinpoint pupils, slow breathing, or no breathing.

A person caring for you can give the naloxone if you stop breathing or don't wake up. Make sure any person caring for you knows where you keep naloxone and how to use it.

Your caregiver must get emergency help after giving a naloxone injection and may need to perform CPR (cardiopulmonary resuscitation) on you while waiting for help to arrive. You may need another injection every 2 to 3 minutes until emergency help arrives.

Before taking this medicine

You should not be treated with naloxone if you are allergic to it.

If possible before you receive a naloxone injection, tell your doctor if:

If you use opioid medicine during pregnancy, your baby could be born with life-threatening withdrawal symptoms, and may need medical treatment for several weeks.

Using naloxone injection while you are pregnant may also cause opioid withdrawal symptoms in your unborn baby. However, having an opioid overdose can be fatal to both mother and baby. It is much more important to treat an overdose in the mother. You must get emergency medical help after using naloxone injection. Be sure all emergency medical caregivers know that you are pregnant and any follow-up doctor knows you received this medicine.

Ask a doctor if it is safe to breastfeed while using this medicine.

How is naloxone given?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Naloxone is injected into a muscle or under the skin, or into a vein. The injection may be given by a healthcare provider, emergency medical provider, or a family member or caregiver who is trained to properly give a naloxone injection.

Naloxone is injected into a vein by a healthcare provider.

If you are a caregiver or family member read all instructions when you first get this medicine. If provided, use the "trainer" device to practice giving an injection so you will know how to do it in an emergency. Ask your doctor or pharmacist if you have any questions. Seek medical help right away if an accidental needlestick injury occurs.

Be sure you know how to recognize the signs of an opioid overdose in the person you are caring for. Overdose symptoms may include:

Even if you are not sure an opioid overdose has occurred, if the person is not breathing or is unresponsive, give the naloxone injection right away and then seek emergency medical care.

Do not assume that an overdose episode has ended if symptoms improve. You caregiver must still get emergency help after giving a naloxone injection, even if the person wakes up. You may need to perform CPR (cardiopulmonary resuscitation) on the person while you are waiting for emergency help to arrive.

Naloxone injection is given in the outer thigh. In an emergency, you may give an injection through the person's clothing.

After injecting naloxone, stay with the person and watch for continued signs of overdose. You may need to give another injection every 2 to 3 minutes until emergency help arrives. Read and carefully follow the instructions provided with this medicine.

Throw away a prefilled syringe after one use, even if there is still medicine left inside.

Store at room temperature away from moisture, heat, and light. Keep the auto-injector in its outer case until you are ready to use it.

Detailed Narcan dosage information

naloxone, nalmefene, Kloxxado, Evzio, Opvee, Rezenopy

What happens if I miss a dose?

Naloxone is used when needed and does not have a daily dose.

What happens if I overdose?

Since naloxone is supplied as the correct dose in a single-dose auto-injector, an overdose is unlikely to occur.

What should I avoid while using naloxone?

Avoid leaving a person alone after giving him or her a naloxone injection. An opioid overdose can impair a person's thinking or reactions.

What other drugs will affect naloxone?

Other drugs may affect naloxone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.

Narcan drug interactions (more detail)

Does Narcan interact with my other drugs?

Enter medications to view a detailed interaction report using our Drug Interaction Checker.

Popular FAQ

How do I get free Narcan emergency kits?

There are several ways to get free Narcan (naloxone) emergency kits, which include, local syringe exchange programs, your insurance company, and state and local health departments or other community health services. Continue reading

How long does Narcan (naloxone) block opiates?

Naloxone blocks opioid receptors from 30 to 120 minutes, but this can be variable and depends upon the dose and how it is given. Some patients may need repeat doses of naloxone. Continue reading

How do you administer Narcan (naloxone)?

Narcan (naloxone) is available in different dose forms and can be given either as an injection or a nasal spray to reverse an opioid overdose. Continue reading

How does Narcan (naloxone) work in an overdose?

Narcan (naloxone) works in an overdose by reversing serious or deadly central nervous system (CNS) depression due to opioids (narcotics), including depressed breathing, extreme drowsiness and loss of consciousness. This effect usually occurs in minutes. Naloxone is considered a pure opioid antagonist and it works by blocking opioid receptors in the body. Continue reading

Is naloxone a controlled substance?

Naloxone is not a controlled substance, according to the US Drug Enforcement Administration (DEA). It is an opioid antagonist used to treat known or suspected opioid overdose, and naloxone nasal spray (sold under the brand name, Narcan) was FDA-approved for sale over-the-counter on March 29th, 2023. It should be available for purchase in places like drug stores, convenience stores, grocery stores and gas stations, as well as online, without a prescription from late summer. Narcan Nasal Spray and naloxone is still available from the pharmacist in all 50 states without a prescription from your doctor.

Is naloxone an opioid antagonist?

Naloxone is a centrally acting opioid receptor antagonist. Naloxone binds with the highest affinity to the mu-opioid receptor subtype in the central nervous system (CNS). Naloxone works to reverse opioid overdose and a form of naloxone (Narcan nasal spray) was FDA-approved for over-the-counter (OTC) sale on 29th March 2023.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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