Naltrexone Overdose: Everything You Need to Know


Naltrexone is a prescription drug that binds to the opioid receptors in the brain, blocking the effects of drugs like cocaine, morphine, and heroin.

That’s why it’s often recommended to people struggling with opioid drug abuse or addiction.

The FDA-approved drug is used after patients detox from an opioid for seven to ten days. It instantly causes withdrawal effects, which can be severe depending on the level of narcotic use.

But can it cause an overdose? Is there any risk to using naltrexone? Find out below.

Can You Overdose on Naltrexone?

While naltrexone doesn’t have any known abuse or addiction risks, it can cause an overdose either directly or indirectly. A direct overdose occurs when patients take a higher-than-prescribed amount of naltrexone.

An indirect overdose happens when people use narcotics with naltrexone. That happens because this drug blocks the euphoric and sedative effects of opioid medications and drugs. This means they won’t experience anything — even if they up the dosage.

Taking an excessive amount of this drug can even lead to death, such as in the case of five Australians overdosing on naltrexone after getting implants.

Causes of Overdosing

Patients might end up overdosing on naltrexone if they:

  • Frequently take large amounts and are addicted to it. For instance, they might overdose on naltrexone if they jump from 50 mg (the typical dose) to 100 mg or even 1500 mg.
  • Inject it directly into their veins, such as through a naltrexone implant, instead of in the glutes.
  • Intentionally or accidentally take more than or double their prescribed dose.

They may also end up overdosing on naltrexone if they ingest high amounts of opioids to overcome its effects.

People become more sensitive to opioids after long-term naltrexone usage, so even a low amount of the drug can cause overdose or death.

What Are the Signs of  a Naltrexone Overdose?

While naltrexone is well tolerated and generally safe, it can cause side effects, especially in the early phase of treatment. These effects include:

  • Fatigue
  • Anxiety
  • Irritability
  • Headache
  • Sleepiness
  • Vomiting
  • Insomnia
  • Toothaches
  • Diarrhea
  • Constipation
  • Restlessness
  • Cold symptoms
  • Libido disorders
  • Lightheadedness
  • Increased tear secretion
  • Dehydration or increased thirst
  • Muscle or joint pains.

Signs that indicate someone may have overdosed on the drug include:

  • Intense pain, blisters, scabs, swelling, lumps, hardness, open wounds, or tissue death at the injection site
  • Extreme fatigue
  • Tinnitus
  • Depression
  • Confusion
  • Blurred vision
  • Fast heartbeat
  • Breathing difficulties or wheezing
  • Unusual bruising or bleeding
  • Hallucinations
  • Seizures or fainting episodes
  • Chest pain
  • Pneumonia
  • Skin rash
  • Loss of appetite
  • Stomach pain in the right upper abdomen (lasting several days)
  • Yellowish color in your eyes or skin
  • Swelling of the tongue, eyes, mouth, or face
  • Dark urine.

People may also experience these symptoms if they’re allergic to naltrexone.

However, regardless of the reason, patients should call 911 or the National Poison Control Center immediately when they notice these signs of overdose or any symptoms that don’t go away.

Who Is Most at Risk of Overdosing on Naltrexone?

Patients have a higher risk of overdosing on naltrexone and shouldn’t take it if they:

  • Are pregnant, want to get pregnant, or are breastfeeding. It isn’t known if naltrexone will harm an unborn baby. However, animal reproduction studies have shown an increased risk of fetal damage.
  • Currently dealing with opioid dependence.
  • Are being treated for an alcohol dependence or opioid use disorder (OUD).
  • Ingest opioid-containing medications for diarrhea, cough, pain, or cold.
  • Are taking methadone.
  • Have hemophilia/other bleeding problems, kidney problems, current liver problems, or other health conditions.
  • Are allergic to naltrexone or any ingredients found in the injectable solution, such as carboxymethylcellulose sodium, polylactide-co-glycolide (PLG), colloidal silicon dioxide, magnesium stearate, polyethylene glycol, and yellow ferric oxide.
  • Experience severe withdrawal symptoms like teary eyes, sweating, anxiety, shakiness, cold or hot flashes, nausea, vomiting, muscle aches, diarrhea, or stomach cramps. Patients should take naltrexone at least seven to ten days after they’ve stopped taking opioid drugs.

People are also at a higher risk of naltrexone overdose if they’re under 18 because of their underdeveloped metabolic system and the lack of drug studies in pediatric populations to fully understand their effects.

What Is the Treatment for Naltrexone Overdose?

If someone is experiencing naltrexone overdose symptoms, they have the following treatment options:

  • Using activated charcoal to slow down drug absorption.
  • Stomach pumping to get the drug out and rinsing it using saline solution.
  • Re-establishing the fluids, minerals, and acid-base balance through IV fluids.
  • Filtering the drug out of the blood using blood washing or hemodialysis.
  • Flushing out any unabsorbed drugs using laxatives.

Some patients may also have to undergo surgery if they experience a severe reaction at the injection site that causes tissue death.

In rare cases, patients might have to undergo a liver or kidney transplant if the reaction affects these organs.

How to Avoid Overdosing on Naltrexone?

To avoid overdosing on naltrexone:

1. Disclose Everything to Your Doctor

It’s important to provide a list of all the medications you take to your healthcare provider before starting naltrexone. This includes:

  • Non-prescription medicines, vitamins, and herbal supplements
  • Prescription medications and opioid drugs.

It’s also crucial to inform your doctor if you have:

  • Kidney or liver problems
  • Medical conditions like hemophilia and hepatic issues
  • Alcohol and opioid dependence.

If someone is being treated for opioid or alcohol dependence and sometimes uses narcotics, they should disclose that as well to avoid the severe onset of withdrawal symptoms once they begin treatment.

2. Avoid Mixing Drugs or Substances

There are 328 medications with the potential to interact with naltrexone:

  • 34 have major effects
  • 294 have moderate effects.

Some medications with major interactions include:

  • Codeine
  • Fentanyl
  • Heroin
  • Lomitapide
  • Morphine
  • Methadone
  • Opium.

Opioid drugs are some of the most dangerous substances you could combine with naltrexone. Patients should try their best to avoid using these before, during, or after starting naltrexone.

3. Seek Support

Dealing with opioid addiction is extremely difficult if you’re alone, so try to seek support.

This can be in the form of therapy, long-term group support, or enlisting the help of family and friends to help you stick to your naltrexone treatment.

However, if you don’t know how to begin, reach out to addiction specialists like Curednation or ask your physician for recommendations and discuss the various treatment and recovery options available to you.

This will help you start on the right track.

Give Yourself the Best Shot at Recovery With Curednation

If you’re thinking about using naltrexone to tackle your opioid addiction and want to give yourself the best shot at a successful recovery, it’s a smart move to go through a medical detox to ensure there aren’t any lingering drugs in your system.

And once you start on injection or oral naltrexone, you should make sure it’s part of a larger plan, like long-term therapy or support groups.

These options can help you boost your chances of success — along with Curednation.

We understand that dealing with opioid addiction is tough — no doubt about it — and while naltrexone can help, it can be difficult to know where to start.

That’s where we can help. Our team can walk you through everything you can expect from naltrexone and help you ensure you always use it safely. Book an appointment today.

Frequently Asked Questions

What Happens If I Drink Alcohol While Taking Naltrexone?

If you drink alcohol while on naltrexone, you won’t experience a “buzz.” However, that doesn’t mean you aren’t at the risk of liver problems.

Alcohol can also cause a moderate drug interaction when combined with naltrexone.

So, if you experience symptoms like fever, nausea, vomiting, itching, chills, abdominal pain, dark urine, yellow skin, or bleeding, you should immediately call 911 because these may be signs of liver damage.

What Happens If I Miss a Dose?

If you miss your oral naltrexone treatment dose and you’ve only lost a few hours, you should try to take it as soon as possible.

But if it’s almost time to take the next dose, only take the next dose. Otherwise, you might end up overdosing.

If you missed your naltrexone injection appointment, schedule another as soon as possible.

Is Naltrexone Safe for the Heart?

While naltrexone is generally safe to take, it may cause severe withdrawal syndrome if given to an opioid addict or someone with heart disease. This syndrome can lead to life-threatening consequences like a heart attack or coronary syndrome.

What Should I Avoid While Using Naltrexone?

If you’re on naltrexone therapy and experiencing dizziness, fatigue, or sleepiness, do not drive a vehicle, perform any heavy lifting, or engage in any other strenuous activity.

You should also avoid high places because of an increased risk of falling.


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