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What Is Naloxone?: Uses, Side Effects, & FAQs

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Medically Reviewed By: Diana Vo, LMFT

April 9, 2024

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Naloxone is an FDA-approved medication that’s formulated to counteract the effects of opioid overdose rapidly. An opioid antagonist, naloxone latches on to opioid receptors in the brain and spinal cord, blocking the rewarding effects of opioids like heroin, fentanyl, and prescription painkillers.

The medication should be used at the first signs of opioid overdose. Naloxone is a temporary remedy, though, and medical attention is required following its application.

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Naloxone can be administered through various methods, including an intranasal spray and an injection. Read on to learn more about this potentially life-saving medication.

What is Naloxone Used For

Naloxone (Narcan) is used to reverse the life-threatening effects of an opioid overdose, including respiratory depression, sedation, and hypotension. Naloxone is the first-line treatment for opioid overdoses.

By binding to mu opioid receptors in the central nervous system, naloxone can restore normal breathing in someone who has overdosed on any type of opioids. The prompt administration of this medication can buy some time until emergency responders arrive.

Individuals who may benefit from access to naloxone include:

  • Those prescribed high doses of opioids for chronic pain management over a long period.
  • People on a rotating regimen of opioid medications.
  • Individuals recently treated and released from emergency medical services for opioid overdose or intoxication.
  • Those using extended-release or long-acting opioid formulations.
  • People undergoing a period of opioid abstinence.
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How Does Naloxone Work

Naloxone acts as an antidote to opioids by stopping the respiratory depression triggered by these substances. It competes with opioid drugs for the same sites on opioid receptors in the brain. By attaching to these receptors, naloxone can reverse the effects of severely slowed breathing and other life-threatening complications caused by opioid overdose

Its mechanism of action is specific to the presence of opioids – without opioids in the system, naloxone remains inactive and induces no effects, making it harmless to anyone not using opioids.

Naloxone is available in two FDA-approved formats: an injectable solution and a prepackaged nasal spray. Regardless of the form, people should familiarize themselves with the product’s instructions and regularly check for its expiration date.

  1. The injectable version of naloxone is manufactured by various companies. Administering this form typically involves drawing the correct dosage from a vial and injecting it into a muscle, although it can also be administered intravenously or subcutaneously. FDA has approved ZIMHITM, a single-use, prefilled syringe designed for subcutaneous or intramuscular injection.
  2. The prepackaged nasal spray, available as generic naloxone, Narcan, and Kloxxado, was developed through research funded by NIDA (National Institute on Drug Abuse). This FDA-endorsed, ready-to-use device is needle-free and designed for simplicity, requiring no assembly. It’s administered by spraying into one nostril while the person is laying prone. Its ease of use makes it accessible to anyone without medical training.

Naloxone Side Effects

Serious side effects warrant immediate attention, as they can be signs of a medical emergency. Both healthcare providers and individuals are urged to report any side effects to FDA’s safety reporting system for medical products, either online or by calling 1-800-FDA-1088.

Individuals who have an allergic reaction to naloxone, characterized by symptoms such as hives, facial swelling, or difficulty breathing, should seek emergency medical care without delay. Those affected should avoid driving or engaging in activities that could be dangerous.

Naloxone use may trigger opioid withdrawal symptoms, requiring immediate medical intervention following its administration. Symptoms of opioid withdrawal can include:

  • Nervousness and restlessness
  • Irritability
  • Muscle aches
  • Weakness
  • Dizziness
  • Diarrhea, stomach pain, or nausea
  • Fever
  • Sneezing or runny nose


What is naloxone?

Naloxone is a medication designed to rapidly reverse the effects of an opioid overdose, effectively blocking the effects of opioids in the brain to prevent severe or life-threatening complications. The medication can restore normal breathing in someone who has overdosed on opioids who is experiencing slowed or stopped breathing.

What are common administration routes for naloxone?

Naloxone can be administered through several routes, including injections (intravenous, intramuscular, or subcutaneous) and a nasal spray. The nasal spray and the intramuscular injection are the most common forms of naloxone used in emergency situations due to their ease of use and rapid onset of action.

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Learn More About Opioid Abuse Treatment at Renaissance Recovery

Whether you have been abusing prescription opioid painkillers or illicit opioids like heroin and fentanyl, all opioid use disorders are highly treatable. When you choose outpatient treatment at Renaissance Recovery, you can pursue sustained recovery from opioid abuse without turning your back on your everyday obligations.

We offer outpatient programs at levels of intensity to suit your personal needs and the severity of your opioid dependence. We can also connect you with licensed medical detox centers if you require assistance with opioid detoxification.

All treatment programs at our rehab in Huntington Beach, California, are personalized to reflect the unique aspects of all opioid addictions. Expect to access any or all of the following treatments:

Call admissions at 866.330.9449 and begin your recovery right away.



At Renaissance Recovery our goal is to provide evidence-based treatment to as many individuals as possible. Give us a call today to verify your insurance coverage or to learn more about paying for addiction treatment.

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Joseph Gilmore has been in the addiction industry for three years with experience working for facilities all across the country. Connect with Joe on LinkedIn.

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