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Naltrexone: Dosages, Uses, and Side Effects

Author: Christine Roth

Last Updated: 4/15/2022

Naltrexone is a drug that is commonly used to aid the recovery of those who are experiencing opioid use disorder and alcohol use disorder. While this drug can be very useful for things such as suppressing cravings, it will not help to manage the side effects of withdrawal. One of the most important things to remember is that this medication is a recovery aid, rather than a cure; this medication is intended to be used under the supervision of a healthcare professional with consistent monitoring alongside other forms of treatment and support such as counseling. The most common dosage of Naltrexone for both opioid and alcohol use disorders is a 380mg intramuscular shot every 4 weeks, which is administered by a specially trained healthcare professional, making further abuse of this medication unlikely. While there may be some unpleasant side effects associated with this medication, it is up to you and your doctor to decide whether the risks outweigh the benefits in regards to aiding and maintaining your sobriety going forwards. 

What is Naltrexone?

Naltrexone is a medication that is primarily used to treat opioid abuse but can also be used to treat alcohol abuse. In regards to opioid abuse, it is used to block the effects of opioid medications, including pain relief, and also helps in reducing cravings. For alcohol abuse or dependency, it is generally used to help reduce cravings which can help you drink less, or stop drinking altogether. 

Naltrexone is not intended to be a cure for alcohol abuse or dependence, but rather an aid to assist with the detox process alongside other treatment plans such as counseling. 

How Does Naltrexone work?

Naltrexone is beneficial for both opioid and alcohol use disorders and works in slightly different ways to aid in the treatment of each. For alcohol use disorders, naltrexone works by binding to the endorphin receptors in the body, therefore, blocking the effects and feelings of alcohol, and helping to reduce cravings. This medication will not stop withdrawal symptoms.

In regards to opioids, Naltrexone blocks the euphoric and sedative effects of opioids such as heroin, morphine, and codeine. Naltrexone does so by binding to and blocking opioid receptors which in turn suppresses cravings.

Because of this binding process, habits of abuse and diversion are not an option with naltrexone. 

How to Take Naltrexone?

Before taking naltrexone, it is important to note that you should not have recently used or been actively using any opioid medication, buprenorphine, methadone, or medicine to treat a cough, cold or diarrhea, or pain for 7-14 days before your first dose as it can cause sudden opioid withdrawal symptoms. Also, you should not be actively consuming alcohol while taking this medication and should be detoxed prior to starting the medication.

The most common way naltrexone is administered is as an intramuscular injection, done by a healthcare professional, every 4 weeks. There may be pain, redness, itching, bruising, swelling or a hard lump at the injection site initially; tell your doctor if these side effects do not subside within 2 weeks or worsen. 

Tell your doctor if you have or have ever been diagnosed with liver disease, kidney disease, or bleeding problems such as hemophilia because you may be at an increased risk for adverse side effects with Naltrexone. 

What are the Uses of Naltrexone?

The main use of Naltrexone is to help treat opioid abuse, with secondary use of assisting in the treatment of alcohol abuse. This medication is used to help stop cravings, but will not treat or prevent withdrawal symptoms. 

This medication is not intended to be used on its own and should be used alongside other forms of treatment for substance abuse such as counseling. 

What are the Side Effects of Naltrexone?

Some of the most common side effects of Naltrexone are listed below.

  • Headache
  • Nausea
  • Tiredness
  • Joint or muscle pain
  • Loss of appetite
  • Vomiting
  • Dizziness
  • Drowsiness
  • Sleep problems
  • Tooth pain
  • Cold symptoms (such as a stuffy nose, sneezing or a sore throat)

It’s important to note that many of these common symptoms also overlap with symptoms of alcohol or opioid withdrawal, most notably stomach pain, vomiting or diarrhea, runny nose, watery eyes, body aches, and trouble sleeping. For those who have recently detoxed or in the process of withdrawing from substance use, it may be difficult to tell whether or not the medication is causing these side effects or amplifying them. It is important to keep an open dialogue with your doctor about what you are experiencing throughout the detox and withdrawal processes as well as while you are on this medication to ensure that it is safe and beneficial to your treatment. 

While allergic reactions with naltrexone are rare, they may present as.

  • Hives
  • Chest pain
  • Wheezing or difficulty breathing
  • Lightheadedness
  • Swelling of the face, lips, tongue, or throat.

In cases of a severe allergic reaction, contact emergency health services immediately. 

If you are experiencing any of the following side effects please contact your health care provider or emergency medical services immediately.

  • Weak or shallow breathing
  • New or worse cough
  • Wheezing or trouble breathing
  • Liver problems (persistent stomach or abdominal pain, dark urine, tiredness or jaundice)
  • Symptoms of depression (such as unusual mood changes, loss of interest in things you once enjoyed, crying, sleep problems, thoughts of hurting yourself or others)
  • If the injection site has
    • Severe pain
    • Swelling
    • Blistering
    • Dark scabs
    • Hard lump (lasting more than 2 weeks)

It is important to keep in mind that these are only some of the most common side effects that are possible with Naltrexone. If you notice any concerning health changes while taking this medication you should speak to your health care provider. 

How Long Do Naltrexone Side Effects Last?

The most common side effects of this medication (such as nausea, vomiting, and dizziness) should subside within a few weeks of treatment or discontinuation of taking the medication. However, some more severe side effects (such as liver problems) may have more severe, long-term consequences if not treated early on. 

What is the Difference Between Naltrexone and Suboxone?

Suboxone is a medication that is a combination of Naloxone and Buprenorphine. The combination of these two drugs is intended to help reduce cravings as well as counteract the effects of opioids. Suboxone is taken orally as either standard tablets or a film that is placed under the tongue to be dissolved. Suboxone is most commonly used to treat opioid use disorders rather than alcohol use disorders but has been seen as useful in helping to ease adverse withdrawal symptoms of those who have stopped drinking and are working towards maintaining sobriety. 

Much like Naltrexone, Suboxone works by attaching to the same brain receptors as opioids and blocking them which helps to prevent intoxication and prevent cravings. The addition of Naloxone in this Suboxone, however, also helps to prevent chances of overdose and abuse as an added safety measure. 

Naltrexone is non-addictive, as there is no presence of synthetic opioids, but you need to wait 7 to 14 days after completely stopping opioid use before beginning the medication as there is a chance for it to cause sudden opioid withdrawal. Suboxone, on the other hand, does pose a risk for physical and psychological dependence, especially when used for an extended period of time. 

While naltrexone can be quit or stopped immediately, suboxone cannot as it may trigger withdrawal symptoms similar to those of opioids and must be weaned off gradually.

As mentioned, it is nearly impossible to overdose on Naltrexone, especially the intramuscular injection as it must be administered by a specially trained doctor. Suboxone, however, does post a higher risk for overdose because there is a synthetic opioid present; large amounts of this medication can lead to toxicity and overdose.  

What is the Difference Between Naltrexone and Naloxone?

Naloxone, more commonly known as Narcan, is a medication that is able to rapidly reverse opioid overdose. Naloxone is an opioid antagonist or inhibitor which works to block the effects of opioids by attaching itself to the opioid receptors in the brain and blocking them. It is considered to be an antidote.

Naloxone is never used on its own to treat opioid use disorder, but rather in conjunction with other medications such as buprenorphine (the combination of these two is known as suboxone) and counseling. The only time Naloxone is used on its own is in emergency situations and cases of overdose in order to reverse the effects of heroin, oxycodone, and morphine. This medication will have no effect on those who do not have opioids in their system, making it ineffective for alcohol poisoning or overdoses. 

The biggest difference between Naltrexone and Naloxone is that Naloxone is a medication only administered on its own in cases of emergency, while naltrexone is routinely taken. 

What is the Difference Between Naltrexone and Buprenorphine?

Unlike Naltrexone, Buprenorphine is a long-lasting, fully synthetic opioid and partial opioid agonist. Buprenorphine produces similar feelings of a high from opiates, but at a much weaker level which may help those trying to recover from opioid addictions to avoid symptoms of withdrawal as well as learn how to manage cravings. It is important to acknowledge that this medication does have the potential for abuse and addiction, but you are at a significantly decreased chance of overdose on this medication than on traditional opioids. 

Similar to Naltrexone, Buprenorphine works by binding to opioid receptors in the brain and blocking other opioids from being able to affect them. However, despite the fact that it can provide a feeling similar to a high, it has a limit to the degree of euphoria or other opioid effects that someone can experience from it, regardless of the amount taken. This medication is rarely used on its own to treat opioid use disorders and is most often used in combination with other medications such as naloxone (the combination of these two drugs is known as suboxone). When used in combination with a drug such as Naloxone the change for abuse is further decreased. 

A high dose of this medication is often considered a last resort for those struggling with treatment-resistant alcohol use disorder, and will not be prescribed to the average person undergoing treatment for alcohol use disorders. Medications such as Naltrexone, Antabuse, or Gabapentin are more commonly prescribed early on in treatment.

Is Naltrexone Addictive?

No, naltrexone is not physically or psychologically addictive. Naltrexone, unlike some other medications used to treat alcohol or opioid use disorder, does not contain any opioids, synthetic or other, and therefore does not pose the risk of addiction. Additionally, because this medicine is most commonly administered as an injection, performed by a healthcare professional, the chances for both addiction and overdose are closely monitored in a professional setting and on a regular basis. 

Is Naltrexone Used for Weight Loss?

Yes, naltrexone can be used for weight loss. Very low doses of naltrexone, when used in combination with bupropion, a reduced-calorie diet, and exercise had proven to be effective for those who suffer from weight gain from emotional eating, or binge eating and help to regulate appetite. Naltrexone is especially helpful for those who are insulin resistant as it helps to regulate the metabolism and modulate cellular resistance to insulin.