Can You Use Naltrexone for Pain Management?

Can You Use Naltrexone for Pain Management?
By T'Keyah Bazin, PharmD 
Updated on January 22, 2024
Medically reviewed by Erika Prouty, PharmD
Very Well Health
https://www.verywellhealth.com/naltrexone-for-pain-management-what-can-it-treat-8419927

Naltrexone is Food and Drug Administration (FDA)-approved to treat alcohol use disorder (AUD) and opioid use disorder (OUD). It is available as an orally administered tablet and a long-acting injectable suspension.

Naltrexone is a non-opioid medication and is classified as an opioid antagonist. This class of medication works by blocking opioid effects.

Due to their mechanism of action (the way a drug works pharmacologically), opioid antagonists can help manage chronic pain and are less likely to lead to opioid dependence, abuse, or addiction.

Preliminary studies suggest naltrexone may provide benefits for chronic pain conditions (pain lasting longer than three months).

This article explains naltrexone's effectiveness in treating various types of pain, such as migraines, fibromyalgia, and neuropathy.

Additionally, this article will discuss the potential side effects of naltrexone, its dosing requirements, alternative uses, and more.

Can You Use Naltrexone for Pain Management?

Overview of Opioid Antagonists
Opioid antagonists are a class of medications that work by blocking opioid receptors in the body’s central nervous system (CNS).

On a chemical level, opiate antagonists block the effects of opioids at the receptor level and help regulate the opioid system by attaching to opioids without activating them.

This prevents the opioids from affecting your body.

Abusing Opioids
Opioids are legally available by prescription only but are often diverted, abused, and used illegally without a prescription.

Opioids are highly addictive, mainly when used over long periods.

Commonly abused opioids include:

  • Codeine
  • Fentanyl
  • Hydrocodone
  • Oxycodone

Commonly Prescribed Opiate Antagonists
Commonly prescribed opiate antagonists, besides naltrexone, include:

  • Narcan (naloxone)
  • Nalmefene (no brand-name form available)
  • Relistor (methylnaltrexone)

Understanding Narcan
The two most commonly prescribed medications opiate antagonists are naltrexone and Narcan.

Naltrexone and Narcan, however, are used in different settings and purposes.

Most notably, Narcan is FDA-approved to treat opioid overdose and reverse opioid-related respiratory depression.

It is frequently used in emergencies and is available with a prescription and over-the-counter (OTC).

However, Narcan, by itself, is not used for pain management.

Nalmefene vs. Relistor
Like naloxone, nalmefene is FDA-approved to treat opioid overdose.

Relistor, conversely, is FDA-approved to treat opioid-induced constipation.

Additionally, Relistor may be used off-label (using a drug for a purpose that it has not been FDA-approved for) in combination with Suboxone (buprenorphine) for this purpose in those who are opioid-dependent and living with chronic pain.

FDA-Approved Uses
Opioid antagonists are FDA-approved for the following uses:

  • Suspected opioid overdose
  • Opioid and alcohol use disorders, such as addiction to street drugs containing opioid derivatives
  • Opioid-induced constipation

What Is Naltrexone?
Naltrexone, an opioid antagonist, is FDA-approved for maintenance treatment of alcohol and OUDs in adults.

There are currently no FDA-approved indications for naltrexone use in the pediatric population.
It is also prescribed as part of a treatment plan for AUD and works by reducing alcohol cravings and pleasurable effects.

Moreover, naltrexone is used to prevent relapse in those who are recovering from opioid dependence by blocking the effects of opioids at the receptor level.

Naltrexone is a promising treatment option because it is not an opioid, and it does not pose an addiction risk.

Forms of Administration
Naltrexone is a prescription-only medication and is administered as an oral tablet (available in generic form only) or an extended-release (ER) injection (administered as brand-name Vivitrol) that is administered once weekly.

Use In Other Products

Off-Label Uses
Naltrexone is not FDA-approved for pain management, but it has been used off-label to treat chronic pain brought on by different conditions, such as:

  • Migraines
  • Fibromyalgia 
  • Multiple sclerosis (MS)
  • Inflammatory bowel disease (IBD)
  • Neuropathy
  • Naltrexone has been used off-label for pain treatment in children, but additional research is needed to determine safety in this population.

How Does It Work?
Naltrexone works by blocking the effects of opioids produced in the body and introduced to the body.

There are some differences in how naltrexone works compared to other opioid antagonists, however.

Notably, naltrexone has a longer duration of action, allowing it to be used for long-term treatment.

Its half-life (the time it takes for the amount of a drug's active ingredient in your body to reduce by half) also makes it suitable for ER formulations.

Naltrexone for Pain Management
During 2021, an estimated 20.9% of American adults (51.6 million people) experienced chronic pain.

In comparison, 6.9% (17.1 million American adults) experienced high-impact chronic pain.

Pain management can be challenging, but medications can help.

The following examines studies that reviewed the efficacy (effectiveness) of naltrexone for pain management.

Efficacy of Low-Dose Naltrexone
Data from clinical trials indicates that low-dose naltrexone is associated with pain relief in some autoimmune, inflammatory, and pain conditions.

The extent of pain relief varies and has not been generalized. Data is limited, and results vary among individuals.

A recent study, however, reviewed the medical charts of people receiving care at a pain clinic who were prescribed low-dose naltrexone.

The study concluded that low-dose naltrexone was associated with pain relief in some autoimmune, inflammatory, and pain conditions.

Neuropathy was the most common pain-related diagnosis with improvement in pain. Those with fibromyalgia-related pain experienced a slight improvement in pain with notable improvements in overall symptoms and quality of life.

The study also found that symptoms may take several weeks to improve after starting therapy. Levels of pain improvement were variable and differed based on pain-related diagnosis.

Data evaluating the use of low-dose naltrexone for fibromyalgia is conflicting.

Some studies demonstrate improvement in pain, but additional research is needed.

Low-Dose vs. High-Dose Naltrexone
The mechanism of naltrexone differs based on the amount of the drug in the body. Naltrexone doses can have different impacts on the body.

Higher concentrations of naltrexone help with drug and alcohol addiction.

Low concentrations help reduce inflammation, making lower doses ideal for pain management.

At low doses, naltrexone blocks opioid receptors and promotes pain relief.

Studies assessing naltrexone for pain management specifically review it at low doses. There are no studies evaluating high-dose naltrexone for pain management.

The critical difference between low-dose and high-dose naltrexone as it relates to treating pain is the variance in the drug's dose-dependent mechanism.

The dosage of naltrexone used to treat substance abuse is greater than the dose used for pain management.

Low-Dose Naltrexone for Cancer
While data is limited, research is promising for low-dose naltrexone used for the treatment of the following cancer types:

  • Bladder
  • Breast
  • Liver
  • Lung
  • Lymph nodes
  • Colon
  • Rectum
  • In animal studies, low-dose naltrexone demonstrates a potential anti-tumor effect.

Additional research is needed to explore further the efficacy of naltrexone for cancer and cancer-related pain.

Dosing Guidelines
Standard naltrexone oral dosage dosing guidelines include the following:

AUD:

Adults: 50 milligrams (mg) daily
Narcotic addiction:
Adults: 25 mg (one-half tablet) for the first dose, then another 25 mg an hour later. From there, the dose is 350 mg weekly.
Onward, your healthcare provider may request that you divide up the weekly dose and take it according to one of the following schedules:
50 mg (one tablet) daily; or 50 mg daily during the week and 100 mg (two tablets) on Saturday; or 100 mg every other day; or 150 mg every three days
Side Effects and Precautions
Like all medications, naltrexone carries the potential for side effects.

However, low-dose (the dosing given for most conditions treated) naltrexone is typically well-tolerated.

The following outlines the common versus rare, severe side effects of naltrexone.

Common Side Effects
Common side effects include vivid dreams, sleep disturbances, nausea, decreased appetite, dizziness, and headache.

Pain, itching, or swelling at the injection site may occur with the injection formulation.

Severe Side Effects
Severe side effects may include confusion, hallucinations, and blurred vision.

The following preexisting conditions may disqualify someone from taking naltrexone:

  • Prior opioid overdose or abuse
  • Opioid use or dependency
  • Liver dysfunction, such as hepatitis (inflammation of the liver)
  • Kidney impairment

Naltrexone may cause liver damage when taken in large doses. However, it is not likely that naltrexone will cause liver damage when taken in recommended doses.

Your healthcare provider can discuss your risk and determine whether naltrexone is an appropriate treatment option.

Safe Consumption Guidelines
You should not use other opioids or alcohol while taking naltrexone. However, no specific guidelines exist for how long you can safely take naltrexone.

However, studies show it may take up to three months to experience initial symptom improvement. Duration of treatment may vary based on the treatment plan.
Naltrexone should not be used in pregnant or breastfeeding people unless otherwise instructed by a healthcare provider. It is not approved for use in children.

It is essential to monitor for new or worsening depression and suicidal thoughts while taking this medication.

Potential for Interaction
Examples of specific medications that shouldn’t be taken alongside naltrexone include:

Opioid medications (such as hydrocodone, oxycodone, morphine, or tramadol-containing medications)
Cytochrome P450 (CYP450) substrates such as Jantoven (warfarin), Buspar (buspirone), or Viagra (sildenafil)
Managing Autoimmune Conditions
Being able to recognize signs and symptoms of autoimmune conditions is an integral part of managing chronic pain.

Autoimmune conditions such as MS or arthritis are often accompanied by chronic pain caused by inflammation.

Symptoms that may indicate an underlying autoimmune condition include fatigue, fever, joint pain or swelling, and skin rashes.

Symptoms specific to multiple sclerosis may include vision problems, muscle weakness, numbness or tingling of the extremities, difficulty staying balanced, and dizziness.

There are several different types of arthritis, and symptoms can vary. A key feature of arthritis is pain, swelling, or stiffness around the joints.

Naltrexone may be able to manage autoimmune condition-related symptoms such as pain, but it cannot cure these conditions.

Your healthcare provider may do additional testing to rule out autoimmune conditions.

Summary
Naltrexone is an opioid antagonist. This class of medication works by blocking opioid effects.

It is FDA-approved to treat alcohol use disorder and opioid dependence It is available in adults as an oral tablet and a long-acting injectable suspension.

Naltrexone is not FDA-approved for pain management, but it has been used off-label to treat chronic pain.

Naltrexone has been used to treat pain associated with fibromyalgia, multiple sclerosis, inflammatory bowel disease, and neuropathy.

Naltrexone use requires close monitoring by your healthcare provider. It would be best to address any questions or concerns regarding naltrexone for pain relief or other treatment options with your healthcare team.

Let your provider know if you have recently stopped using opioids. Do not stop taking naltrexone without discussing it with your healthcare provider.