Naltrexone treats alcohol dependence and opioid drug abuse. It will not be started unless there has not been ingestion of opiates for at least 7-10 days.

Naltrexone Overview

Reviewed: October 1, 2013

Naltrexone is a prescription medication used to treat alcohol dependence and opioid drug abuse. Naltrexone belongs to a group of drugs called opiate antagonists. It works by reducing the craving for alcohol and blocking the effects of opiate medications and opioid street drugs.

This medication comes in tablet form and is taken once a day, with or without food.

Naltrexone is also available as an injection to be injected into the muscle by a healthcare provider. 

A common side effect of naltrexone is stomach upset.

Naltrexone injection may make you feel dizzy and sleepy. Do not drive a car, operate machinery, or do other dangerous activities until you know how it affects you.

Patient Ratings for Naltrexone

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  • Alcoholism

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Uses of Naltrexone

Naltrexone is a prescription medication used to treat alcohol dependence and opioid drug abuse.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Naltrexone Brand Names

Naltrexone may be found in some form under the following brand names:

Naltrexone Drug Class

Naltrexone is part of the drug class:

Side Effects of Naltrexone

Serious side effects have been reported with naltrexone.

Common side effects of naltrexone injection include:

  • nausea. Nausea may happen after your first naltrexone injection and usually improves within a few days. Nausea is less likely with future injections of naltrexone.
  • sleepiness
  • headache
  • dizziness
  • vomiting
  • decreased appetite
  • painful joints
  • muscle cramps
  • cold symptoms
  • trouble sleeping
  • toothache

Common side effects of naltrexone tablets include:

  • stomach cramps
  • nausea
  • headache
  • dizziness
  • nervousness 
  • restlessness
  • fatigue
  • difficulty falling or staying asleep
  • vomiting
  • anxiety
  • bone or joint pain
  • nasal symptoms

This is not a complete list of naltrexone side effects. Ask your doctor or pharmacist for more information.

Tell your doctor if you have any side effect that bothers you or that does not go away.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Naltrexone FDA Warning

Naltrexone has the capacity to cause hepatocellular injury when given in excessive doses.

Naltrexone is contraindicated in acute hepatitis or liver failure, and its use in patients with active liver disease must be carefully considered in light of its hepatotoxic effects.

The margin of separation between the apparently safe dose of naltrexone and the dose causing hepatic injury appears to be only five-fold or less. Naltrexone does not appear to be a hepatotoxin at the recommended doses.

Patients should be warned of the risk of hepatic injury and advised to stop the use of naltrexone and seek medical attention if they experience symptoms of acute hepatitis.