Naltrexone

Naltrexone (nal TREKS one) is a generic medication prescribed for treating certain substance use disorders in adults. Naltrexone belongs to a group of drugs called opioid antagonists.

Medically reviewed by Dena Westphalen, PharmD on May 12, 2023
Written by Alex Brewer, PharmD, MBA

Specifically, the Food and Drug Administration (FDA) has approved naltrexone for use in adults with:

• alcohol use disorder
• opioid use disorder

This article describes naltrexone’s uses, side effects, and more. Below you’ll also find some coupon options to help save on the cost of naltrexone.

Common questions about naltrexone

Below you’ll find answers to a few commonly asked questions about naltrexone.

Is it safe to take naltrexone with bupropion (Wellbutrin XL, Wellbutrin SR)?

Yes, if your doctor prescribes both medications to you. Naltrexone and bupropion aren’t known to interact with each other.

In fact, the prescription medication Contrave contains both bupropion and naltrexone in a single pill. Contrave is prescribed with diet and exercise to help adults with weight loss.

Talk with your doctor if you have additional questions about medications that may be taken with naltrexone, including bupropion.

How does naltrexone compare with naloxone?

Naltrexone and naloxone are both opioid antagonists. This means they block the effects of opioid drugs.

However, naltrexone and naloxone have different uses. Naltrexone is prescribed to treat alcohol use disorder (AUD) and opioid use disorder (OUD). On the other hand, naloxone is used in emergencies to treat symptoms of and reverse an opioid overdose. Naltrexone does not treat opioid overdose and should not be used for this purpose.

If your doctor prescribes an opioid drug, they may suggest keeping naloxone on hand in the event of an overdose. But if your doctor prescribes naltrexone, you should not take or use an opioid drug.

Talk with your doctor if you’d like to learn more about how naltrexone compares with naloxone.

Can naltrexone be used for pain or fibromyalgia?

Maybe. Naltrexone isn’t approved to treat pain or fibromyalgia. However, it may be prescribed off-label for these uses. With off-label use, a drug that’s approved for treating certain conditions is prescribed for another purpose.

If you have questions about off-label use of naltrexone, talk with your doctor or pharmacist.

What is naltrexone’s half-life? How does the drug work?

Naltrexone has a half-life of about 4 hours. This means that it takes about 4 hours for your body to clear half of a dose of the drug after you take it.

Naltrexone is an opioid antagonist. It works by blocking the effects of opioids in your body. It’s not fully understood how the drug works to treat AUD. But studies of the drug show it can lower alcohol consumption.

Naltrexone begins working within a few hours after you take your first dose. Keep in mind that naltrexone is used to help treat substance use disorders as part of a treatment plan. This plan can also include counseling and social support. The drug shouldn’t be relied on to treat substance use disorder on its own. Your doctor can provide more information on when you may notice naltrexone working.

If you have questions about how naltrexone works, talk with your doctor or pharmacist.

Is naltrexone a controlled substance?

No, naltrexone isn’t a controlled substance.

Controlled substances are drugs or substances that have the potential for misuse or dependence. (With misuse, a drug is taken for a purpose or in a way that a doctor has not prescribed. With dependence, your body becomes reliant on a drug to function as usual.)

Hydrocodone and fentanyl are two examples of controlled substances. Illegal drugs, including the opioid heroin, are also controlled substances.

Some medications used to treat substance use disorders are controlled substances, such as buprenorphine/naloxone (Suboxone) and methadone. Your doctor can answer questions you may have about how naltrexone compares to these medications.

What brand names are available for naltrexone?

There are no brand names available for naltrexone tablets.

There’s a brand-name liquid called Vivitrol, which is given as an injection into a muscle. It contains naltrexone. Similar to naltrexone oral tablets, Vivitrol is prescribed to help treat AUD and OUD in adults. Naltrexone oral tablets are taken every day. On the other hand, Vivitrol injections are given by a healthcare professional once every 4 weeks.

If you have questions about brand name options for naltrexone, talk with your doctor or pharmacist.

Side effects of naltrexone

Naltrexone may cause mild or serious side effects. More common mild side effects of naltrexone and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age, overall health, and any other medications you take.

To learn more about naltrexone’s side effects, talk with your doctor or pharmacist. You can also read the prescribing information* for naltrexone.

* To view naltrexone’s prescribing information, see the “Article resources” section below.

Mild side effects

More common mild side effects reported with some forms of naltrexone are listed below.

This article doesn’t include all possible mild side effects of the drug. To learn more about naltrexone’s side effects based on the form, see the prescribing information* for naltrexone.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Naltrexone oral tablet’s mild side effects include:

• nausea
• headache
• dizziness
• nervousness
• mild allergic reaction*

* To view naltrexone’s prescribing information, see the “Article resources” section below.
† For details about this side effect, see the “Interactions and warnings for naltrexone” section below.

Serious side effects

Serious side effects of naltrexone are listed below.

This article doesn’t include all possible serious side effects of the drug. To learn more about naltrexone’s side effects based on the form, see the prescribing information* for naltrexone.

With many drugs, serious side effects are possible but not common. If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

In general, naltrexone’s serious side effects include:

• depression
• liver damage
• severe opioid withdrawal, if naltrexone is taken while you’re still taking an opioid drug
• suicidal thoughts or behaviors
• severe allergic reaction†

* To view naltrexone’s prescribing information, see the “Article resources” section below.
† For details about this side effect, see the “Interactions and warnings for naltrexone” section below.

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

• Ask the tough question: “Are you considering suicide?”
• Listen to the person without judgment.
• Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
• Stay with the person until professional help arrives.
• Try to remove any weapons, medications, or other potentially harmful objects.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Click here for more links and local resources.

Uses of naltrexone

The Food and Drug Administration (FDA) approves prescription drugs such as naltrexone for certain conditions. Approved uses for naltrexone are described below.

Use for alcohol dependence or blocking the effects of opioids

Doctors may prescribe naltrexone oral tablet for treating alcohol use disorder and opioid use disorder (OUD), including blocking the effects of opioid drugs. It’s used for this purpose in adults. It’s usually prescribed as a long-term treatment.

With alcohol or opioid use disorder, you use alcohol or opioids in a way that causes problems in your daily life. For example, you may avoid work or school obligations. Using alcohol or opioids long term causes changes in your brain that can make it even harder to stop using these substances.

Symptoms of opioid or alcohol use disorder include:

• missing work, school, or social obligations due to using alcohol or opioids
• continuing to use alcohol or opioids, even though alcohol or opioid use is causing you harm
• having the inability to cut back or stop using alcohol or opioids, even if you want to
• avoiding activities or hobbies you normally enjoy due to using alcohol or opioids

Naltrexone is prescribed together with counseling and other support services for treating alcohol or opioid use disorder.

In certain situations or if you’re still using opioids, doctors may not prescribe naltrexone oral tablet for treating OUD.. Naltrexone must not be taken if you have used opioids in the past 7 to 10 days due to the risk of severe withdrawal symptoms.

Before your doctor prescribes naltrexone for you, they’ll likely ask whether you’ve recently used or received any opioid drugs.

Interactions and warnings for naltrexone

Below, you’ll find information about naltrexone’s possible interactions and warnings.

Interactions of naltrexone

For some medications, certain things may affect how the drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take naltrexone, ask your doctor to check for possible interactions. Be sure to tell them about any of the following you take or use:

• prescription medications
• over-the-counter medications
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for naltrexone” section below.

Warnings for naltrexone

Some people should not take naltrexone and others should take it cautiously.

Naltrexone could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether naltrexone is a safe option for you.

Ask your doctor about specific warnings for naltrexone, and be sure to tell your doctor about your:

• current health, including any allergies to medications
• past health conditions or surgeries

Allergic reaction

Naltrexone can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to naltrexone or any of its ingredients, your doctor will likely not prescribe naltrexone. They can tell you about medications that are safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to naltrexone, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

Pregnancy or breastfeeding and naltrexone

Information about naltrexone and pregnancy and breastfeeding is described below.

Naltrexone and pregnancy

It’s not known whether naltrexone should be taken during pregnancy. But there are risks with having untreated substance use disorder, including alcohol use disorder (AUD) or opioid use disorder (OUD), while pregnant. (Keep in mind that naltrexone is used for treating AUD and OUD.)

If you’re planning a pregnancy or can become pregnant, talk with your doctor about substance use disorder treatment options during pregnancy. Together, you can discuss the risks and benefits of your treatment options and decide whether or not you should take naltrexone during pregnancy.

Naltrexone and breastfeeding

It’s not known whether naltrexone should be taken while breastfeeding. If you’re currently breastfeeding or planning to do so, talk with your doctor before taking this medication.

Dosage of naltrexone

The dosage of naltrexone your doctor prescribes may vary based on your condition and certain other factors. Talk with your doctor about the dosage you should take.

Taking naltrexone

Naltrexone oral tablet is taken by mouth, with or without food.

Your doctor will talk with you about how to take naltrexone. They’ll explain how much to take and how often. Always follow your doctor’s recommendation. 

Overdose of naltrexone

You should not take more naltrexone than your doctor prescribes. For some drugs, doing so may lead to serious side effects or overdose.

If you think you’ve taken too much naltrexone, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

Naltrexone coupon

You may be able to save money on your prescription for naltrexone by using our Perks discount coupons. They can be found at the end of this article.

If you have questions about how to pay for naltrexone, talk with your doctor or pharmacist.

Note: Optum Perks coupons cannot be used with insurance copays or benefits.

What to ask your doctor

This article describes naltrexone’s uses and dosage, ways to save on cost, and more. Let your doctor know if you have questions about naltrexone or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• How do naltrexone tablets compare with Vivitrol injections for my condition?
• What pain relievers are safe to take while I’m treated with naltrexone?
• Are there treatments to relieve side effects that naltrexone can cause?

 Article resources

• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm
• Naltrexone hydrochloride- naltrexone hydrochloride tablet, film coated. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/838a1e88-1179-4a2a-a737-8ce008bb96a7/spl-doc

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.