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Naloxone vs. Naltrexone

Elena Hill, MD, MPH profile image
Medically Reviewed By Elena Hill, MD, MPH • Updated Oct 24, 2023 • 3 cited sources

Naloxone and naltrexone are both opioid antagonist medications. Naloxone can rapidly reverse an opioid overdose, while naltrexone is a long-lasting medication used to treat opioid use disorder (OUD) by blocking drug-related euphoria. 

Key Facts

  • Naloxone and naltrexone are opioid-blocking medications.
  • Naloxone works quickly to reverse an overdose. Naltrexone lasts longer, so it can prevent euphoria if you relapse.
  • Naloxone is an over-the-counter medication. Naltrexone requires a prescription.

Naloxone & Naltrexone for OUD Treatment

People with OUD benefit from medications like naloxone and naltrexone. Chronic opioid misuse changes brain chemistry, making relapse cues hard to resist. Naloxone and naltrexone can both keep a relapse from becoming fatal. 

Only one of these medications (naltrexone) is used in Medication for Addiction Treatment (MAT) programs. Using long-lasting therapies like naltrexone can help people build their sober skills. Medications are part of how Bicycle Health helps people to rebuild their lives. 

What Is Naloxone?

Naloxone (Narcan) is a rapidly acting medication that can save someone’s life in the case of an opioid overdose. 

Naloxone comes in a pre-measured spray or injection, ensuring users don’t need to determine the dosage for naloxone when trying to save a life. When it enters the body, naloxone attaches to receptors immediately, removing other opioids from their receptors and preventing overdose.

The U.S. Food and Drug Administration (FDA) first approved naloxone in 2016. In March 2023, the FDA approved over-the-counter versions of the drug.[1] 

This drug isn’t intoxicating, and people don’t misuse it. Expanding availability could save lives. Anyone with naloxone could step in and stop an overdose. 

While administering this medication during an overdose could save someone’s life, it won’t keep them from relapsing again. Naloxone is not considered an MAT option as a result. 

What Is Naltrexone?

Naltrexone (Vivitrol, ReVia) treats both alcohol use disorder (AUD) and OUD. It works by preventing intoxication. 

Naltrexone binds to the mu-opioid receptor, and blocks the rewarding effects of opioids and alcohol. The action can help you break a psychological attachment to drugs.[2] 

Naltrexone comes in two forms: pills (50-100 mg daily) and injections (380 mg injection once per month). The FDA approved naltrexone in 2010 to treat both alcohol use disorder and opioid use disorder as directed by doctors via a prescription.[3]

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What Are the Differences Between Naloxone & Naltrexone?

Understanding the differences between naloxone and naltrexone is critical, as these two medications do very different things. Only one (naloxone) can save a life during an overdose. And only one (naltrexone) can help treat an OUD long-term. 

Comparison of Naloxone & Naltrexone

UsesReverses an opioid overdose in minutesMakes opioids less reinforcing, so a slip is less likely to become a full-blown relapse episode 
Administration RoutesNasal spray or injection Oral tablets or injection 
Frequency TakenOnly during an overdose Oral: Varies from daily to once every three days Injection: Once per month
DosageNarcan nasal spray comes in 4 mg doses, but stronger versions existOral: Tablets are sold in 50 mg doses Injection: 380 mg
Time to WorkMinutes About an hour 
Side EffectsTriggers immediate opioid withdrawal symptoms, such as nausea, diarrhea and muscle aches Reactions at the injection site, liver damage and allergic pneumonia 
CostAround $50 Oral: About $30-$50 (monthly)Injection: $1,100 plus the cost of the shot 
Generic AvailableYesOral pills come in generic form, but the injections don’t 
AvailabilityAvailable over the counter so people can help during an emergency A prescription is required 

How to Choose Between Naloxone & Naltrexone 

If you’re struggling with OUD, naloxone and naltrexone could be part of your recovery toolkit. Your doctor can help you decide which one (or both) are helpful for your recovery.

Most people consider these factors:

  • Use: Naloxone and naltrexone are very different medications. Do you need help in case of an emergency? Do you also need help with day-to-day temptation?
  • Cost: Naloxone is significantly less expensive than naltrexone. 
  • Side effects: Naltrexone can cause serious side effects. If they concern you, another MAT option could be a better choice. 

Are There Other Options Available to Treat OUD? 

Two medications (apart from naltrexone) that are FDA approved to treat OUD are methadone and Suboxone (buprenorphine/naloxone).

Suboxone is a prescription medication that works differently from naloxone and naltrexone. It contains buprenorphine, which can help to block opioid cravings and keep you from relapsing to drugs. 

If naltrexone isn’t helping to keep your OUD under control, Suboxone might be better. Talk to your doctor to learn more about naltrexone and Suboxone as treatments for OUD.

Naloxone vs. Naltrexone: Comparing Opioid Disorder Medications 

Naloxone and naltrexone have similar sounding names and uses and thus are easily confused. This article will clarify the differences. 

Naloxone and naltrexone are both opioid antagonist medications, meaning that they reverse the effects of opioids. When an individual ingests opioids, the opioids bind to opioid receptors in the brain, and turn those receptors “on”, creating various effects including euphoria, decreased pain, and more concerningly, respiratory depression and potential for overdose. 

In contrast, both naloxone and naltrexone are opioid antagonist medications, which means they bind to opioid receptors in the brain and turn those receptors “off”. In this way, they can prevent or reverse and overdose of opioids. 

Naloxone is a quick acting medications that can be administered intranasally or through an IV to help reverse an opioid overdose. It is sold either by prescription or over the counter (depending on your State of residence) and can be carried around and administered in case of emergency to anyone who is suspected of having overdosed on opioids. Its effects occur within just a few minutes of administration. Naloxone helps to reverse an overdose but it is NOT used as a long term medication to prevent opioid misuse. 

Naltrexone, in contrast, is a pill medication (also available in injectable form, called Vivitrol) that is used more long term to prevent the use of opioids. It is one of three medications available to help treat opioid use disorder (OUD), including methadone and Suboxone. Naltrexone is also often used as a treatment for alcohol use disorder. Unless naloxone, it is a pill that is taken daily to prevent opioid or alcohol use. In addition, it can be injected monthly under the skin to also help prevent opioid or alcohol use. 

If you have questions or confusion about the differences between these medications, reach out to your doctor for further clarification. 

Naloxone vs. Naltrexone Frequently Asked Questions 

We’ve compiled some of the most frequently asked questions about naloxone vs. naltrexone. 

Can I use naloxone and naltrexone at the same time?

Yes, you can use both naloxone and naltrexone at the same time. For example, if you take naltrexone daily for OUD and then use opioids and overdose, you can still safely administer naloxone (Narcan) to help reverse that overdose.

Do naloxone and naltrexone have any drug interactions?

Naloxone drug interactions are plentiful. If you’re using opioids, naloxone will interact with them. Other medications (like antidepressants) can interact too. Naltrexone can interact with opioids and some anti-diarrhea medications.

How do naloxone and naltrexone compare with other OUD treatments?

Technically, naloxone isn’t an OUD treatment. It blocks an overdose without preventing the next one. Naltrexone is effective in making a slip less reinforcing. But other MAT options can reduce cravings and withdrawal symptoms too.

Medically Reviewed By Elena Hill, MD, MPH

Elena Hill, MD; MPH received her MD and Masters of Public Health degrees at Tufts Medical School and completed her family medicine residency at Boston Medical Center. She is currently an attending physician at Bronxcare Health Systems in the Bronx, NY where ... Read More

  1. Information about naloxone and nalmefene. U.S. Food and Drug Administration. Published June 21, 2023. Accessed June 28, 2023.
  2. Singh D, Saadabadi A. Naltrexone. [Updated 2023 May 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from:
  3. Naltrexone prescribing information. U.S. Food and Drug Administration. Published October 2010. Accessed June 28, 2023.

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