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Naloxone Injection

Generic Name: naloxone (injection) (nah LOX one)
Dosage Forms: injectable solution (0.4 mg/mL; 1 mg/mL; 2 mg/0.4 mL)

Medically reviewed by Sanjai Sinha, MD. Last updated on April 19, 2021.

What is naloxone?

Naloxone blocks or reverses the effects of opioid medication, including extreme drowsiness, slowed breathing, or loss of consciousness. An opioid is sometimes called a narcotic.

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

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

Naloxone is also used to help diagnose whether a person has used an overdose of an opioid.

Warnings

Naloxone is used to treat a possible opioid overdose. An opioid overdose can be fatal, and symptoms may include severe drowsiness, pinpoint pupils, slow breathing, or no breathing.

In an emergency situation it may not be possible before you are treated to tell your caregivers about your health conditions or if you are pregnant or breast feeding. Make sure any doctor caring for you afterward knows that you have received naloxone.

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. You may need another injection every 2 to 3 minutes until emergency help arrives.

Drinking alcohol can increase certain side effects of naloxone.

Naloxone may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be alert.

If you are using any narcotic pain medication, the pain-relieving effects of the narcotic will be reversed while you are also receiving this medicine.

Before taking this medicine

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

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

  • you have heart problems; or

  • you are pregnant or breastfeeding.

Using naloxone while you are pregnant may cause opioid withdrawal effects 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 this medicine. Be sure all emergency medical caregivers know that you are pregnant.

If you use opioid medicine while you are pregnant, your baby could become dependent on the drug. This can cause life-threatening withdrawal symptoms in the baby after it is born. Babies born dependent on opioids may need medical treatment for several weeks.

In an emergency, you may not be able to tell caregivers if you are pregnant or breastfeeding. Make sure any doctor caring for your pregnancy or your baby knows you received naloxone.

How is naloxone given?

Use naloxone exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets.

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

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.

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

  • slowed breathing, or no breathing;

  • very small or pinpoint pupils in the eyes;

  • slow heartbeats; or

  • extreme drowsiness, especially if you are unable to wake the person from sleep.

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 must 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 injected into a muscle 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. Follow all medication instructions carefully.

Store at room temperature away from moisture and heat. Do not use the medicine if it has changed colors or has particles in it. Call your pharmacist for new medication.

Dosing information

Usual Adult Dose for Opioid Overdose:

Initial dose: 0.4 mg to 2 mg IV; alternatively, may give IM or subcutaneously
-If desired response is not obtained, doses should be repeated at 2 to 3 minute intervals
-If no response is observed with a total dose of 10 mg, the diagnosis of opioid-induced or partial opioid-induced toxicity should be questioned

-Administer 0.4 mg (1 actuation) IM or subcutaneously into the anterolateral aspect of the thigh (through clothing if necessary)
-If desired response is not achieved, a second dose may be administered after 2 or 3 minutes; additional doses may be administered every 2 to 3 minutes until emergency medical assistance arrives
Comments:
-IV route is recommended in emergency situations since it has the most rapid onset of action.
-The duration of action of some opioids exceed that of this drug, therefore, repeat doses may be needed; the need for repeat doses will depend on the amount, type, and route of administration of the opioid being antagonized.

Usual Adult Dose for Reversal of Opioid Sedation:

Initial dose: 0.1 to 0.2 mg IV at 2 to 3 minute intervals to the desired degree of reversal
-Supplemental doses administered IM have been shown to produce a longer lasting effect

Intravenous Infusion:
-A concentration of 0.004 mg/mL may be administered by IV infusion; titrate in accordance with patient's response

Comments:
-For the partial reversal of opioid depression following the use of opioids during surgery, smaller doses of naloxone are usually sufficient; larger than necessary doses may result in significant reversal of analgesia and increases in blood pressure.

Usual Pediatric Dose for Opioid Overdose:

Neonates:
Initial dose: 0.01 mg/kg IV, IM, or subcutaneously; repeat dose every 2 to 3 minutes as needed

Children:
Initial dose: 0.01 mg/kg IV; if desired response is not obtained, may give 0.1 mg/kg IV
-If IV route is not available may give IM or subcutaneously in divided doses

-Administer 0.4 mg (1 actuation) IM or subcutaneously into the anterolateral aspect of the thigh (through clothing if necessary); if desired response is not achieved, a second dose may be administered after 2 or 3 minutes; additional doses may be administered every 2 to 3 minutes until emergency medical assistance arrives
-Under 1 year of age: Thigh muscle should be pinched while administering injection

Comments:
-Neonatal opioid withdrawal syndrome may be life-threatening and should be treated according to protocols developed by neonatology experts.
- To avoid precipitating opioid withdrawal symptoms, consider use of a naloxone product that can be dosed according to weight and titrated to effect.
-The duration of action of some opioids will exceed that of this drug, therefore, repeat doses may be needed; the need for repeat doses will depend on the amount, type, and route of administration of the opioid being antagonized.
-Patients should remain under continued surveillance; if a patients responds and relapses back into respiratory depression, additional doses should be given.
-Additional supportive and/or resuscitative measures may be helpful while awaiting emergency medical assistance.

Usual Pediatric Dose for Reversal of Opioid Sedation:

Neonates:
Initial dose: 0.01 mg/kg IV, IM or subcutaneously at 2 to 3 minute intervals to the desired degree of reversal

Children: 0.005 mg to 0.01 mg IV at 2 to 3 minute intervals to the desired degree of reversal

Intravenous Infusion:
-A concentration of 0.004 mg/mL may be administered by IV infusion; titrate in accordance with patient's response

Comments:
-For the partial reversal of opioid depression following the use of opioids during surgery, smaller doses of naloxone are usually sufficient; larger than necessary doses may result in significant reversal of analgesia and increases in blood pressure.

What happens if I miss a dose?

Since this medicine is used when needed, naloxone has no dosing schedule.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using naloxone?

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

Naloxone side effects

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

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

  • nausea, vomiting, diarrhea, stomach pain;

  • fever, sweating, body aches, weakness;

  • tremors or shivering, fast heart rate, pounding heartbeats, increased blood pressure;

  • goose bumps, shivering;

  • runny nose, yawning; or

  • feeling nervous, restless, or irritable.

Sudden withdrawal symptoms in a baby younger than 4 weeks old may be life-threatening if not treated the right way. Symptoms include 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.

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.

What other drugs will affect naloxone?

Other drugs may interact with naloxone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all your current medicines and any medicine you start or stop using.

Popular FAQ

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.

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.

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

More FAQ

Further information

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

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