Uses

What is naltrexone used for?

Naltrexone is commonly used for the following conditions: 

  • To help people with an alcohol use disorder who have already stopped drinking maintain their ability to no longer drink alcohol.
  • To help people with an opioid use disorder who have already stopped using opioids maintain their ability to no longer use opioids. 

Naltrexone may also be used for other conditions as determined by your healthcare provider.

Naltrexone is also available as an injection. See Vivitrol for more information.

How does naltrexone work (mechanism of action)?

Naltrexone works by blocking the effects of opioids.  

How is naltrexone supplied (dosage forms)?

Naltrexone is available as 50 mg oral tablets that are taken by mouth.

How should I store naltrexone?

Naltrexone should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place.

Side Effects

What are the most common side effects of naltrexone?

The most common side effects of naltrexone are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Nausea or vomiting
  • Stomach cramps
  • Joint or muscle pain
  • Headache 
  • Dizziness 
  • Nervousness, anxiety, restlessness
  • Tiredness
  • Trouble sleeping

There may be other side effects of naltrexone that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of naltrexone?

While less common, the most serious side effects of naltrexone are described below, along with what to do if they happen.

Severe Allergic Reactions. Naltrexone may cause allergic reactions, which can be serious. Stop taking naltrexone and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking naltrexone. Keep all appointments you have to get your blood checked. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine (pee)
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Suicidal Thoughts and Depression. Naltrexone may cause suicidal thoughts or actions. Depression is an important cause of suicidal thoughts, especially in people with a history of alcohol use disorder. If you are about to harm yourself, call 911 or call or text 988, the Suicide & Crisis Lifeline. Caregivers and family should also monitor people taking naltrexone for suicidal thoughts and depression. Contact a healthcare provider right away for any of the following symptoms

  • New or increased feelings of anxiety, depression, or other unusual changes in mood or behavior
  • Suicide attempt
  • New or increased thoughts of suicide or death

Warnings & Precautions

Who should not use naltrexone?

Allergies to Ingredients. People who are allergic to any of the following should not take naltrexone.

  • Naltrexone
  • Revia
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific naltrexone products they stock.

Drug Interactions. Naltrexone should not be used while you are using certain other medicines. Before using naltrexone, tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Current Opioid Use and Dependence. People who are currently using prescription and/or illicit opioids, including buprenorphine, should not take naltrexone. If you take naltrexone while taking opioids, it could lead to withdrawal symptoms, which may require you to go to the hospital. Opioid use can cause physical dependence, which means your body relies on the medicine. If you have flu-like symptoms or anxiety when you stop opioids, you may have physical dependence. Physical dependence is not necessarily a sign that you have developed a substance use disorder. Your healthcare provider may do a urine screen or other tests to help them determine if it is safe for you to take naltrexone. Before taking naltrexone, be sure to tell your healthcare provider about any use of prescription and/or illicit opioids. 

Opioid Withdrawal. You may have symptoms if you have been using prescription and/or illicit opioids and suddenly stop taking them. People who are in opioid withdrawal should not take naltrexone.  Tell your healthcare provider before you take naltrexone if you have any of the following symptoms of opioid withdrawal. 

  • Anxiety 
  • Sleeplessness 
  • Yawning
  • Fever
  • Sweating 
  • Teary eyes 
  • Runny nose 
  • Goosebumps 
  • Shakiness
  • Hot or cold flushes 
  • Muscle aches or twitches
  • Restlessness
  • Nausea and vomiting 
  • Diarrhea
  • Stomach cramps

What should I know about naltrexone before using it?

Do not take naltrexone unless it has been prescribed to you by a healthcare provider. Take it as prescribed.

Do not share naltrexone with other people, even if they have the same condition as you. It may harm them.

Keep naltrexone out of the reach of children and pets.

The use of naltrexone is not associated with the development of tolerance or dependence.

Naltrexone is not known to affect the use of cocaine or other non-opioid drugs of misuse.

It is possible that you may be more sensitive to the effects of prescription or illicit opioids as naltrexone wears off, a dose is missed, or after it is stopped. Resuming the doses of opioids you were using before starting naltrexone can be very dangerous and can potentially lead to death. You can also have a bad reaction where you stop breathing if you take opioids to try to overcome the effects of this medicine. Should you feel the need to use opioids while on or after stopping naltrexone, contact your healthcare provider. 

It is very important that you stop taking opioids before taking naltrexone. Tell your healthcare provider the last time you took any prescription or illicit opioid. Your healthcare provider needs to know this information to determine if it is safe for you to take naltrexone. 

Make sure that you and your caregiver have the medicine naloxone, which is used to reverse the effects of opioids. Talk with your healthcare provider about how to get and administer naloxone. If naloxone is needed, also call 911 to get emergency help.

Tell all of your healthcare providers that you are using naltrexone, so that they can provide you with appropriate care. In case of an emergency, people using naltrexone should carry an identification card stating that they are on naltrexone.  

Naltrexone can help you no longer use opioids and/or drink alcohol, especially when it is combined with counseling and support. Attend all therapy or support groups that may have been recommended to you.   

It is possible that people with an alcohol use disorder may begin to use other substances of misuse such as narcotics or opioids. Should you begin to use other substances of misuse, call your healthcare provider. 

Naltrexone can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how naltrexone affects you.

Naltrexone can be used for as long as you feel it is helping. Should you wish to stop naltrexone, call your healthcare provider. 

What should I tell my healthcare provider before using naltrexone?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if naltrexone is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your healthcare provider about any of the following.

  • Kidney problems
  • Liver problems
  • Depression 
  • History of suicidal thoughts or attempts
  • Use of prescription and/or illicit opioids

Pregnancy. It is not known if or how naltrexone could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant. Your healthcare provider will advise you if you should take naltrexone while you are pregnant or trying to get pregnant.

Breastfeeding. It is not known if naltrexone passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should take naltrexone while breastfeeding.

Interactions

Does naltrexone interact with foods or drinks?

There are no known interactions between naltrexone and foods or drinks.

There are no known interactions between naltrexone and alcohol.

Does naltrexone interact with other medicines                                                                              

Always tell your healthcare provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using/taking naltrexone.

  • Disulfiram, a medicine commonly used to help people with an alcohol use disorder who are no longer drinking alcohol continue to not drink alcohol. 
  • Thioridazine, a medicine used to help certain mental health conditions like schizophrenia 
  • A mixed agonist/antagonist or partial agonist opioid analgesic, such as buprenorphine (Butrans, Sublocade), butorphanol, and others, which is used to treat certain types of pain or opioid use disorder 
  • An opioid, such as oxycodone, morphine, codeine, methadone, fentanyl, diphenoxylate, or loperamide, which is a medicine used for certain types of pain, diarrhea and cough.

This may not be a complete list of medicines that can interact with naltrexone. Always check with your healthcare provider.

Does Naltrexone interact with other drugs you are taking?
Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much naltrexone?

If you or someone else has used too much naltrexone, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of naltrexone?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

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