naloxone hydrochloride injection

Medically Reviewed on 5/25/2022

Generic Name: naloxone

Brand Names: Narcan, Evzio, Narcan Nasal Spray

Drug Class: Opioid Antagonists

What is naloxone (Narcan), and what is it used for?

Naloxone is a man-made opioid antagonist, which means that it blocks the action of opioid medications such as morphine and related drugs.

Naloxone works by binding to mu-receptors in the brain that opioids use to produce their effect on pain and other symptoms. By binding to mu receptors, naloxone reverses opioid activity in the body.

Doctors and other health care professionals use naloxone for partial or complete reversal of respiratory depression caused by synthetic (man-made) or natural opioids (narcotics), and to diagnose suspected or known acute opioid overdose.

Doctors also use naloxone to increase blood pressure in people with septic shock.

What are the side effects of naloxone?

Side effects of Naloxone include:

What is the dosage for naloxone?

Adult dosage

  • Opioid overdose: 0.4 to 2 mg intravenous (IV), intramuscular (IM), or subcutaneous injection every 2 to 3 minutes as needed; however, after10 mg administered, it is recommended that its use be reassessed as the symptoms may not be due to opiate activity.
  • Reversal of opiate activity: 0.1 to 0.2 mg IV, IM, or subcutaneous injection every 2 to 3 minutes as needed.

Dosage for children (5 years or older OR 20 kg or less):

  • Opioid overdose: Initially 0.01 mg/kg IV; may increase to 0.1 mg/kg if necessary.
  • Postoperative opioid depression: 0.005 to 0.01 mg IV every 2 to 3 minutes as needed.

Nasal spray dosage

  • The initial dose of the nasal Spray in adults and pediatric patients is one spray into one nostril. An additional dose may given if the response is not adequate.
  • If needed, administer additional doses every 2 to 3 minutes.
  • Additional doses should be administered to alternate nostrils using a new naloxone nasal spray.

Which drugs interact with naloxone?

  • Large doses of Naloxone are required when used together with buprenorphine since buprenorphine binds and dissociates slowly from mu receptors.
  • Large doses of Naloxone may cause respiratory distress.

Pregnancy and breastfeeding

  • There are no adequate studies done on Naloxone to determine safe and effective use in pregnant women.
  • It is not known whether Naloxone enters breast milk; therefore, it is best to be cautious before using it in women who are breastfeeding.

What else should I know about naloxone?

  • Naloxone is available as injection of 0.4 and 1 mg/ml, auto Injector of 0.4 mg/0.4 ml, and nasal spray of 2mg and 4mg.
  • Naloxone should be stored at room temperature 20 C to 25 C (68 F to 77 F).
  • Narcan and Evzio are the brand names available for naloxone in the US.
  • Narcan is available in generic form. You need a prescription from your doctor or other health care professional to obtain Narcan.


What are opioids used to treat? See Answer


Naloxone hydrochloride injection is a drug used to treat signs and symptoms of drug and other substance abuse. Side effects, drug interactions, dosage, and pregnancy safety information should be reviewed prior to administering this medication. Naloxone is available as a generic drug, or under the brand names Narcan, Evzio, and Narcan Nasal Spray. You need a prescription from your health care provider for this drug.

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Medically Reviewed on 5/25/2022
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