Warning: Undefined array key "titleWrapper" in /home/customer/www/invigormedical.com/public_html/wp-content/plugins/seo-by-rank-math/includes/modules/schema/blocks/toc/class-block-toc.php on line 103
Skip to main content

Naltrexone vs. Naloxone: How Are These Opioid Blockers Different?

Nov 1, 2023
Naltrexone vs. Naloxone: How Are These Opioid Blockers Different?

Naltrexone vs. Naloxone sound very similar, and they both reverse the effects of opioids.

However, these two medications are quite different. Naltrexone, brand name Vivitrol, is a medication that is approved to treat alcohol use disorder and opioid use disorder. Naltrexone is used as part of a treatment plan extending over weeks to months.

Naloxone, brand name Narcan, quickly blocks the effects of opioids, including ones that can be fatal. It is fast-acting, but its effects do not last long. Naloxone buys time to get someone who has overdosed on opioids to an emergency room for further treatment.

Opioid use is common. According to a 2021 SAMHSA survey, 9.2 million people misused opioids in the survey year. About 16.5% of the population (46 million people) meet the criteria for having a substance use disorder. Of these, about half misuse alcohol, and the other half misuse drugs.

Opioids can cause physical dependence and addiction and have a high potential for overdose. In 2021, over 100,000 people died from an overdose. Almost three in every four deaths involved synthetic opioids.

Examples of opioids include heroin, fentanyl, oxycodone, hydrocodone, codeine, and morphine.

What Is Naloxone? 

Naloxone is a medication that reverses the effects of opioids. Since opioid drugs can slow respiration and impair consciousness, naloxone is a lifesaving medication when it is given quickly.

Narcan (naloxone) does not require a prescription. In fact, many schools, colleges, restaurants, and other public spaces dispense Narcan to treat opioid overdoses.

Naloxone can be administered as an injection or a nasal spray.

Because naloxone must be given quickly, there has been a push to make it readily available in many public spaces and to train people on how to administer it.

Naloxone does not cause harm if a person has another medical condition that is mistaken for an opioid overdose, such as a heart attack or diabetic coma. Administering naloxone can save a person’s life, even if you are not sure whether they overdosed on opioids.

Signs of an opioid overdose include:

  • Being unconscious
  • Having shallow or undetectable breathing
  • Being limp
  • Having a slow or irregular heartbeat
  • Having a bluish tinge to lips, tongue, or fingertips

After receiving naloxone, a person who has overdosed on opioids will begin to arouse and recover. It is important to call for emergency help because naloxone is short-acting.

Woman with a headache

How Naloxone Works

Naloxone can reverse the effects of opioids. Naloxone binds to opioid receptors in the brain and throughout the body more tightly than opioid drugs.

When naloxone is given to someone who has taken an opioid, naloxone displaces opioid drugs from their receptors and reverses their effects.

This is lifesaving because opioids can slow your breathing to where it is life-threatening and cause you to become unconscious.

What Is Naltrexone? 

Naltrexone is approved to treat opioid use disorder and alcohol use disorder. It is only available by prescription obtained through an in-person or online medical appointment.

Naltrexone is a versatile medication. Besides treating substance use disorders, naltrexone can be prescribed in a very low dose to treat chronic pain or inflammation. Researchers are still working to understand the many ways low-dose naltrexone can be used to improve health and treat disease.

Naltrexone can also be combined with other medications. For example, naltrexone/bupropion is a combination medication that induces weight loss better than either medication can on its own.

Naltrexone vs. Naloxone: How Are These Opioid Blockers Different?

How Naltrexone Works

Naltrexone also binds to opioid receptors in the brain. By blocking these receptors for extended periods, naltrexone can reduce the pleasure and reward people get from using opioids, alcohol, or consuming highly palatable foods.

When you drink alcohol, use opioids, or consume highly palatable foods, your brain releases dopamine, a chemical messenger. Dopamine reinforces that these are all pleasurable activities. Increased dopamine release makes you crave these substances.

Over time, excessive alcohol and opioid use changes your brain’s sensitivity to natural opioids and dopamine. This can cause physical dependence and addiction.

Naltrexone blocks opioid receptors, which decreases the amount of natural opioids and dopamine your brain produces. Because your brain does not get the same burst of pleasure, your cravings subside.

Two key areas of the brain, the hypothalamus and the reward pathway, control appetite and cravings. Naltrexone/bupropion binds to receptors here, reducing food cravings and hunger and increasing satiety with eating. Naltrexone/bupropion is one of six approved medications for weight loss.

A man holding pills trying to decide Naltrexone vs. Naloxone

Ways Naltrexone vs. Naloxone Differ

Naloxone and naltrexone are both approved medications that help people who take opioids. Naloxone can rescue a person from an opioid overdose. Naltrexone is used after a person stops using opioids to prevent a relapse.

Naloxone is available by prescription and over the counter. It is easy to administer and does not cause harm, even if the cause of decreased respirations and alertness is not an opioid overdose.

Naloxone is designed to be administered quickly. It is short-acting, and treatment must be followed by emergency care. Once naloxone is metabolized in the body, opioids can continue to have their effect.

Anyone can administer naloxone to someone in need and potentially save their life.

Naltrexone is a prescription medication that can be prescribed in many forms, including:

  • At a higher dose to treat alcohol use disorder and opioid use disorder.
  • At a lower dose to improve pain and reduce inflammation, among other things.
  • Combined with bupropion to treat obesity and induce weight loss.

Naltrexone is longer-acting and more likely to cause side effects and have drug interactions than naloxone. Be sure to supply your doctor and pharmacist with your complete medical history so they can check to see if you are at increased risk for any naltrexone side effects.

People who request a prescription for naltrexone can have many motivations. For example, naltrexone/bupropion is frequently prescribed to assist with weight loss as part of a more comprehensive lifestyle treatment plan. 

Conclusion to Naltrexone vs. Naloxone

Navigating the complexities of opioid blockers like naltrexone and naloxone is crucial for informed health decisions. If you’re considering the unique benefits of naltrexone, especially in low doses for conditions such as weight loss or autoimmune disorders, Invigor Medical offers a secure option to buy low dose naltrexone. With their guidance, you can embark on a treatment path that’s tailored to your needs. Explore Invigor Medical’s website for more insights.

Frequently Asked Questions

Are naltrexone and naloxone the same thing?

No, naltrexone and naloxone are not the same thing. While both are opioid antagonists, they have different mechanisms of action and are used for different purposes. Naloxone is primarily used as an emergency treatment for opioid overdose, while naltrexone is used to manage alcohol and opioid dependence.

What is the difference between naloxone and Narcan?

Naloxone is the generic name of the medication, while Narcan is a brand name for a nasal spray formulation of naloxone. Both contain the same active ingredient and are used to rapidly reverse opioid overdose.

What is the most common side effect of naltrexone?

The most common side effects of naltrexone include nausea, headache, dizziness, fatigue, and insomnia. These side effects are typically mild and temporary.

Why is naloxone preferred over naltrexone?

Naloxone is often preferred over naltrexone in emergency situations such as opioid overdose because it works rapidly to reverse the effects of opioids and restore normal breathing. Naltrexone, on the other hand, is used for longer-term management of opioid and alcohol dependence.

While we strive to always provide accurate, current, and safe advice in all of our articles and guides, it’s important to stress that they are no substitute for medical advice from a doctor or healthcare provider. You should always consult a practicing professional who can diagnose your specific case. The content we’ve included in this guide is merely meant to be informational and does not constitute medical advice.

Naltrexone vs. Naloxone: How Are These Opioid Blockers Different?

Leann Poston, M.D.

Dr. Leann Poston is a licensed physician in the state of Ohio who holds an M.B.A. and an M. Ed. She is a full-time medical communications writer and educator who writes and researches for Invigor Medical. Dr. Poston lives in the Midwest with her family. She enjoys traveling and hiking. She is an avid technology aficionado and loves trying new things.


Fill out the form below, and one of our treatment specialists will contact you.

Featured Articles

Naltrexone vs. Naloxone: How Are These Opioid Blockers Different?

What To Know About The Ice Hack For Weight Loss Diet 

As the number of people in the U.S. who are overweight or have obesity continues to climb, so too do new weight loss diet fads. These seemingly quick and easy eating plans appeal to people hoping t…
Naltrexone vs. Naloxone: How Are These Opioid Blockers Different?

What Is Brain Fog and How to Beat It

Brain fog is not a diagnosable medical condition. Instead, it is a constellation of symptoms affecting thinking and memory. Many people have experienced temporary brain fog. We all have those days …
LDN Boost

Medication Information: LDN Boost

Everything you need to know about LDN Boost.