Naltrexone is a generic drug prescribed for opioid use disorder and alcohol use disorder in adults. Naltrexone comes as an oral tablet that’s typically taken once per day.

Naltrexone belongs to a drug class called opioid antagonists. Naltrexone oral tablet isn’t available as a brand-name version.

Keep reading for specific information about the dosage of naltrexone oral tablet, including its strength and how to take the medication. For a comprehensive look at naltrexone, including details about its uses, see this article.

Note: This article describes typical dosages for naltrexone oral tablet provided by the drug’s manufacturer. When taking naltrexone oral tablet, always follow the dosage prescribed by your doctor.

Read below for recommended dosages of naltrexone oral tablet and other details about the medication.

Naltrexone form

Naltrexone comes as an oral tablet.

Naltrexone strength

Naltrexone tablet comes in one strength of 50 milligrams (mg).

Typical dosages

The following information describes dosages that are commonly prescribed or recommended. However, be sure to take the dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Dosage for opioid use disorder

Doctors may prescribe naltrexone to help treat opioid use disorder (OUD), also called opioid dependence. It’s prescribed as part of a treatment program that may include counseling, support groups, and more.

If your doctor prescribes naltrexone for OUD, your starting dose will likely be 25 mg. Typically, you’ll take this once per day. If you don’t experience withdrawal symptoms* after a day, your doctor may increase your dosage to 50 mg per day. This is the recommended dosage for the treatment of OUD.

For more information about your specific dosage, talk with your doctor.

* Withdrawal symptoms are side effects that can occur when you stop taking a drug that your body has become dependent on. Naltrexone oral tablet may cause withdrawal symptoms if you’ve taken opioids within 10 days of starting naltrexone. To learn more about naltrexone’s possible side effects, see this article.

Dosage for alcohol use disorder

Naltrexone is also approved to help treat alcohol use disorder (AUD), also called alcohol dependence. Doctors prescribe naltrexone along with counseling and other AUD treatments.

In this case, the recommended dose of naltrexone is 50 mg. You’ll usually take this once per day.

Talk with your doctor if you have questions about your dosage.

Long-term treatment

Naltrexone is meant to be taken as a long-term treatment for OUD. If you and your doctor determine that naltrexone is safe and effective for you, you’ll likely take it long term.

For AUD, the recommended treatment time is up to 12 weeks. But your doctor may prescribe the drug for longer if you both feel this is best for treating your condition.

Before you start taking naltrexone, your doctor will discuss your treatment plan with you.

Naltrexone comes as a tablet you swallow whole. The drug’s prescribing information doesn’t say whether to crush, chew, or split the tablets. Be sure to take your dose with a full glass of water. You can take your dose with food if naltrexone upsets your stomach.

It may be helpful to take your naltrexone dose around the same time of day. This helps maintain a steady level of the drug in your body so naltrexone can work effectively.

If you have trouble swallowing tablets, see this article for tips on how to take this form of medication. You can also talk with your doctor or pharmacist.

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


Some pharmacies offer labels with large print, braille, or a code you scan with a smartphone to convert text to speech. If your local pharmacy doesn’t have these options, your doctor or pharmacist might be able to recommend a pharmacy that does.

If you’re having trouble opening medication bottles, ask your pharmacist about putting naltrexone oral tablet in an easy-open container. They also may recommend tools that can make it easier to open bottles.

If you miss a dose of naltrexone oral tablet, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose and take your next scheduled dose. Do not take two doses to make up for the missed one. If you’re unsure whether you should take a missed dose or skip it, talk with your doctor or pharmacist.

To help make sure that you don’t miss a dose, try using a medication reminder. This can include setting an alarm or putting a note where you’ll see it, such as on your bathroom mirror or bedside table. You could also download a reminder app on your phone.

It’s important that you do not take more naltrexone oral tablet than your doctor prescribes. For some medications, taking more than the recommended amount may lead to harmful effects or overdose. To learn about naltrexone’s side effects, see this article.

If you take more than the recommended amount of naltrexone

Call your doctor right away if you believe you’ve taken too much naltrexone. Another option is to call America’s Poison Centers at 800-222-1222 or use its online tool. If you have severe symptoms, immediately call 911 or your local emergency number, or go to the nearest emergency room.

Below are some frequently asked questions about naltrexone oral tablet.

Can naltrexone be used for weight loss? If so, what’s the dosage?

Naltrexone oral tablet isn’t approved for use on its own to help with weight loss. But the drug may be prescribed off label for this or other uses. With off-label use, doctors prescribe a drug for a purpose other than what the Food and Drug Administration (FDA) approved it for. Naltrexone tablet is FDA approved to help treat opioid use disorder (OUD) and alcohol use disorder (AUD) in adults.

Since naltrexone tablet isn’t approved as a weight loss aid, the drug’s manufacturer doesn’t provide recommended dosages for this use. If your doctor prescribes naltrexone tablet, they’ll determine the dosage that’s right for you.

If you’d like to learn more about naltrexone tablet for weight management, talk with your doctor.

Note: Naltrexone is one of two active ingredients in Contrave (naltrexone/bupropion). Contrave is FDA approved to help with weight loss. If you’re interested in Contrave treatment, talk with your doctor for more information.

What is the recommended maximum dosage of naltrexone?

The prescribing information for naltrexone oral tablet doesn’t specify a recommended maximum dosage. The recommended daily dose of naltrexone for its approved uses is 50 milligrams (mg).* (Naltrexone tablet is approved to help treat OUD and AUD in adults.) For details about naltrexone dosages, see the “Naltrexone dosage” section above.

If you have questions or concerns about your naltrexone tablet dosage, talk with your doctor or pharmacist. Do not increase your dosage unless your doctor recommends doing so.

* In cases of supervised treatment, a doctor may administer a daily dose of more than 50 mg naltrexone oral tablet. This would be part of an alternative dosing schedule. If you have questions about this, talk with your doctor.

How long does it take for naltrexone to start working?

Naltrexone oral tablet begins to work after you take your first dose. Naltrexone is fully absorbed into your body within 1 hour.

Based on how naltrexone works, you may not feel the medication working in your body. And you may not feel a reduction in cravings or other symptoms of your condition right away. But your doctor will monitor you during treatment to check whether the naltrexone is working to treat your condition. (Naltrexone tablet is prescribed to help treat OUD and AUD in adults.)

Talk with your doctor if you have questions about what to expect with naltrexone tablet treatment.

The dosage in this article is the typical dosage provided by the drug’s manufacturer. If your doctor recommends naltrexone oral tablet for you, they’ll prescribe the dosage that’s right for you. Always follow the dosage that your doctor prescribes.

As with any drug, never change your dosage of naltrexone tablet without your doctor’s recommendation. If you have questions about the dosage of naltrexone that’s best for you, talk with your doctor.

Besides learning about dosage, you may want other information about naltrexone tablet. These additional articles might be helpful:

Disclaimer: Medical News Today 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.