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Naloxone (Narcan, Evzio) : Administration, Side Effects, and Dosage

What Is Naloxone?

Naloxone is an opioid antagonist, which means that it bind to and blocks the body’s opioid receptors from agonists such as heroin, oxycodone, and morphine.This effectively blocks the biological response of opioids, the most dangerous overdose being respiratory depression. Naloxone can also be given after surgery to minimize any post-operative sedations caused by opioids used during the procedure.2

Typically, naloxone is given to reverse the dangerous medical consequences of an opioid overdose. In emergency settings, it is often found in a liquid form that is injected into a vein, a muscle, or just under the skin.1,2,3 The liquid form of the drug is regularly used by paramedics, emergency room doctors, and other medically trained first responders.It is also available as a nasal spray, which allows naloxone to be sprayed into the nose—making it easier to use.1

Naloxone may be available with or without a prescription from a doctor, depending on the state. It is sold under the brand names Narcan (an FDA-approved prefilled single-dose nasal spray) and Evzio (which is formulated as an emergency, single-use auto-injector).2,3,4

Naloxone is not used to treat dependence or addiction to opioids or opioid use disorder. Instead, it blocks opioid receptors long enough to help a person recover from an overdose; the should then receive immediate medical attention. People who are dependent on opioids should receive the proper intervention and treatment for opioid addiction.

How Do You Get It?

According to the Substance Abuse and Mental Health Services Administration (SAMHSA), people who are at high risk for opioid overdoses may be able to obtain naloxone, such as those who:5

  • Take opioids in high doses for pain management.
  • Have been discharged from the hospital due to a previous opioid overdose.
  • Are in mandatory detox or abstinence programs for addiction to opioids.
  • Take certain types of long-acting opioids.

Certain states require a prescription for a pharmacist to dispense naloxone, while others allow pharmacies to provide naloxone directly to consumers without a doctor’s prescription.1

Administration of Naloxone

Naloxone may be obtained by people at risk of an opioid overdose to keep on-hand for emergencies. The pharmacist or the doctor who provides the naloxone can demonstrate how to use the medication.5 In many cases, a person in the midst of an opioid overdose is not able to administer this treatment to themselves. For this reason, a caregiver is often trained how to administer naloxone if needed. 1,2,5

Naloxone may be administered three ways:1,5

  1. Injectable, which typically requires professional training.
  2. Auto-injector, provided through an autoinjector that is designed to be simple to use.5
  3. Nasal spray, provided by a device that sprays the medication into the nose.

Police and emergency medical personnel often carry naloxone to treat opioid overdoses immediately on the scene, rather than losing valuable time waiting to get to an emergency room.

Some areas have adopted widescale community-based naloxone distribution as well as public access opioid overdose kits that include naloxone.11,12 Regardless of whether or not a person is trained in how to administer naloxone, an attempt should still be made to follow the illustrated instructions to administer the medication in the event of an overdose. Note that injections can be given through clothes if needed.As of December 2018, 46 states and the District of Columbia have laws that protect caregivers and first responders from liability if they give someone naloxone for an overdose.6

Recognizing an Overdose

Opioid users and their caregivers should be aware of the signs of an opioid overdose. A person who has overdosed will typically show some or all of these symptoms:

  • Extreme sleepiness and frequent episodes of nodding off.
  • Not being awakened when spoken to loudly or when someone rubs the person’s chest firmly.
  • Shallow breathing or not breathing at all.
  • Small, constricted pupils. 2

If an overdose is suspected, caregivers or bystanders should first call 911 and then administer naloxone.Further, emergency services should always be called to make sure that the person who overdosed receives a proper evaluation and further medical treatment.

A naloxone dose typically doesn’t last very long, and overdose symptoms will often return within a few minutes of receiving the medication. However, repeated doses can be given every few minutes until medical help arrives.2

Opioid Withdrawal Symptoms

Naloxone may lead to the very rapid onset of opioid withdrawal symptoms in users who have developed a dependence on opioids. These symptoms can be quite unpleasant and my include:1,2,5

  • Nausea.
  • Vomiting.
  • Sweating.
  • Shaking.
  • Stomach cramps.
  • Muscle twitching.
  • Fever.
  • Diarrhea.
  • Extreme restlessness.

How Effective Is Naloxone?

Naloxone has shown effectiveness in treating opioid overdoses.9,10

  • Opioid overdose deaths were estimated to be reduced by 11% in 19 communities that implemented a naloxone distribution program in Massachusetts.
  • The Centers for Disease Control and Prevention reported that, from 1996-2015, Narcan reversed the overdose of 27,000 people.
  • The Food and Drug Administration (FDA) has stated that naloxone is an essential means for first responders, medical providers, and the general public to reverse opioid overdoses and and begin to reduce overdose deaths. Efforts are being made to increase access to all forms of naloxone—especially for those who have a history of overdose or a substance use disorder.12

Frequently Asked Questions

What Is the Difference Between Naloxone and Naltrexone?1,2,5,6,10,13

Naloxone is used in emergency situations to prevent a fatal overdose from opioids. Naltrexone is an addiction treatment medication that works by blunting the euphoric effects or “rush” of opioids.

Does Naloxone Get You High?

No. Naloxone is non-addictive and, in fact, nearly immediately reverses or blocks the high users normally experience from opioids.

Can Naloxone Cause Sudden, Complete Opioid Withdrawal?

Yes. In some cases, the administration of naloxone will cause someone who is dependent on opioids to suddenly develop the symptoms of acute opioid withdrawal.

How Do Overdoses Happen?

When people use street drugs, such as heroin, it is easy for them to overdose – particularly when they build up a tolerance and need to take more and more of the drug to get high. The same thing can happen when someone misuses a prescription drug such as oxycodone.

But accidental overdoses can occur even when someone takes opioids as prescribed. For example, a person may misread the instructions and take more pills than were prescribed. Or a person may forget they already took the prescribed opioid medication and take another dose, which results in too much of the drug in that person’s system.

Will Naloxone Help Me Go ‘Cold Turkey’ and Detox at Home?

No, naloxone alone is not designed to help with opioid withdrawal symptoms or to help detox from opioids. Naloxone is only designed to stop the negative life-threatening effects of an opioid overdose.

Can Naloxone Be Used for Pregnant Women?

The FDA states there is limited available data on naloxone use in pregnant women which aren’t sufficient to inform a drug-associated risk. However, there are risks to the fetus of opioid-dependent mother with use of naloxone.

What if I Give Someone Naloxone and Something Bad Happens?

Currently, 46 states and Washington, D.C. provide legal protection for “Good Samaritans” who give naloxone in good faith to help save a person’s life.

  1. National Institute on Drug Abuse. (2018). Opioid Overdose Reversal with Naloxone (Narcan, Evzio).
  2. U. S. National Library of Medicine. (2016). MedlinePlus: Naloxone Injection.
  3. ADAPT Pharma. (n.d.). Narcan.
  4. Kaleo. (n.d.). Evzio.
  5. Substance Abuse and Mental Health Services Administration. (2019). Naloxone.
  6. The Network for Public Health Law. (2018). Legal Interventions to Reduce Overdose Mortality: Naloxone Access and Overdose Good Samaritan Laws.
  7. Substance Abuse and Mental Health Services Administration. (2019). Buprenorphine.
  8. U.S. National Library of Medicine. (2018). MedlinePlus: Buprenorphine Sublingual and Buccal (opioid dependence).
  9. National Institute on Drug Abuse. (2017). Naloxone for Opioid Overdose: Life-Saving Science.
  10. Substance Abuse and Mental Health Services Administration. (2019). Naltrexone.
  11. Castillo, Tessie. (2018). Harm Reduction Strategies for the Opioid Crisis. NCMJ, 79(3), 192-194.
  12. U.S. Food and Drug Administration. (2019). Statement on continued efforts to increase availability of all forms of naloxone to help reduce opioid overdose deaths.
  13. U.S. Food and Drug Administration. (2018). FDA Briefing Document: Joint Meeting of the Anesthetic and Analgesic Drug Products Advisory Committee and the Drug Safety and Risk Management Advisory Committee, December 17-18, 2018.