Naltrexone Dosages for Adults: Your GoodRx Guide

Naltrexone (Vivitrol) is a medication that treats alcohol use disorder (AUD) and opioid use disorder (OUD). In fact, using a medication such as naltrexone is the recommended treatment for OUD and AUD.

If you’re prescribed naltrexone, knowing how to take it will help you get the most benefit. Here, we’ll give you the details on naltrexone dosages for adults, what to do if you miss a dose, and more.

What’s the typical naltrexone dosage for adults?

Your dose will depend on which naltrexone form you’re using and what condition you’re treating.

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Naltrexone comes as an oral tablet and as an extended-release injection (Vivitrol) that goes into a muscle (called an intramuscular injection). The injection has to be administered by a healthcare professional.

You can take naltrexone tablets with or without food. But taking them with or after meals may help prevent digestive side effects, such as diarrhea.

Good to know: Regardless of why you’re receiving naltrexone, you’ll need to be opioid free for 7 to 10 days before you start receiving it. If you have opioids in your system when you start naltrexone, you’re likely to experience uncomfortable opioid withdrawal symptoms. This is because naltrexone is an opioid antagonist (blocker). It works by blocking the effects of opioids. So opioid withdrawal can occur if opioids are in your blood when you start taking naltrexone. Your prescriber may order blood work to check for opioids before prescribing naltrexone.

AUD

The typical oral naltrexone dosage for AUD is 50 mg once daily. Some people may take up to 100 mg once daily, but this isn’t as common.

The Vivitrol dosage for AUD is 380 mg every 4 weeks (once a month). It should be injected in the buttock muscles by a healthcare professional.

How long to continue naltrexone for AUD depends on several factors. These include personal preference, how severe your AUD is, and how you’re tolerating naltrexone.

OUD

Oral naltrexone isn’t a first-choice medication option for OUD. But if it’s used, the typical dosage is 50 mg once daily. Your prescriber may initially try a lower dosage to make sure opioids have left your system.

The typical Vivitrol dosage for OUD is the same as AUD: 380 mg dose every 4 weeks (once a month). Injectable naltrexone is a better choice than oral naltrexone for OUD. But other FDA-approved OUD medications are usually preferred: methadone or buprenorphine-containing medications, such as Suboxone (buprenorphine / naloxone).

How long you’ll need to take naltrexone for OUD depends on several factors, including the severity of your OUD and your preferences. Some people need medication for OUD indefinitely.

Reducing binge drinking (off-label use)

Naltrexone oral tablets may also be used off-label to reduce binge drinking (drinking too much alcohol too quickly). Since this is an off-label use, there’s no FDA approved dosage.

When naltrexone is used to reduce binge drinking, it’s usually taken on an as-needed basis. This means you’ll take it before a situation that you think might cause you to binge drink. The naltrexone dosage used in studies was 50 mg before the event.

If you’re interested in naltrexone to help reduce your drinking, talk to your prescriber. They can help you determine if this is a good option for you.

Are there any dosage adjustments for medical conditions?

Naltrexone doesn’t have specific dosage adjustments for medical conditions. But if you have kidney or liver disease, you may need a lower dose of naltrexone (or to avoid it altogether). This is because the kidneys and liver metabolize (break down) and eliminate (get rid of) naltrexone. If they aren’t working as well as expected, naltrexone may build up in the body and increase your risk of side effects.

Can you drink alcohol while taking naltrexone?

If you’re using naltrexone to treat OUD or AUD, it’s best to minimize or avoid consuming alcohol. Naltrexone and alcohol aren’t known to interact, but alcohol can be harmful. And it can set you back on your goals to quit drinking or quit opioids.

If you’re struggling to quit drinking with naltrexone, talk to your prescriber. They may adjust your dose or recommend another medication for AUD. Other options include acamprosate and disulfiram.

What happens if you miss a dose of naltrexone?

What happens if you miss a dose of naltrexone depends on the form you’re using.

• Missing a dose of oral naltrexone. If you forget to take a dose of oral naltrexone, take it as soon as you remember. But if it’s already the following day, skip the missed dose and resume your usual dosage schedule. Don’t take more than one dose of oral naltrexone at a time.

• Missing a Vivitrol injection. If you miss a Vivitrol dose, call your prescriber immediately to reschedule your appointment for the injection. It’s important that you receive your injection as soon as possible. Sticking to your dosage schedule helps keep a steady amount of Vivitrol in your system at all times. Waiting too long between Vivitrol doses puts you at greater risk of opioid overdose if you were to return to opioid use.

What should you do if you take too much naltrexone?

If you take too much oral naltrexone, you may experience side effects, such as nausea, dizziness, and headache. If you think you’ve taken too much naltrexone, call the Poison Control Center at 1-800-222-1222. If your symptoms feel severe or life-threatening, call 911 or head to the emergency room.

How to save on naltrexone

There are a few ways to save on naltrexone. Oral naltrexone is a generic medication, but injectable naltrexone is available only as brand-name Vivitrol.

• Save with GoodRx. Generic oral naltrexone may cost less than $[naltrexone low price] with a free GoodRx discount.

• Save with a copay savings card. If you have commercial insurance, you may be eligible to save up to $500 a month on out-of-pocket costs for brand-name IM Vivitrol using a savings card from the manufacturer.

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Written by:

Alex Brewer, PharmD, MBA

Alex Brewer, PharmD, MBA, is a licensed pharmacist specializing in chronic disease and health and wellness. Upon completing his residency, he worked in the managed care field, conducting medication therapy management and adherence counseling sessions with Medicaid, Medicare, and private insurance patients, before transitioning to a career in medical writing.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

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