What Is Naltrexone Used For?

Naltrexone, sold under the brand names Revia and Vivitrol, is an FDA-approved medication-assisted treatment (MAT) option for both opioid use disorder and alcohol dependence. Unlike methadone or buprenorphine, naltrexone isn’t an opioid itself. It’s non-addictive, doesn’t cause physical dependence, and won’t trigger withdrawal symptoms if someone stops taking it.

The medication works by blocking opioid receptors in the brain, which prevents the euphoric effects of both opioids and alcohol. Because of this, anyone starting naltrexone needs to be fully detoxed first; taking it while opioids are still in the system can trigger an uncomfortable withdrawal reaction.

How Naltrexone Works

Naltrexone is a type of drug that’s known as an opioid antagonist. It blocks other opioids from activating receptors in the brain by occupying those receptors itself. Because of this, it can effectively block the euphoric and sedative effects of opiates and alcohol, which prevents a person from getting high.

Naltrexone should not be taken while a person is still actively drinking or using opioids. Individuals should be fully detoxed from all substances before starting naltrexone.

Read about how naltrexone works

When Will Naltrexone Take Effect?

Naltrexone works relatively quickly, within one to two hours of administration depending on the type of formulation taken.

Formulations include:

• Intramuscular Injection (Vivitrol): The effects of Vivitrol, injected once a month, reach an initial peak about two hours after injection.
• Tablet Form: The oral tablet form of naltrexone takes effect shortly after the first dose, within one to two hours.
• Implant: The effects of a naltrexone implant release slowly over a 10- to 12-week period. Note: Naltrexone implants are not currently available in the U.S.

Various factors, including a person’s metabolic rate, substance use, and genetics can affect how long it takes for naltrexone to take effect.

Side Effects Of Naltrexone

Like any drug, naltrexone may cause some side effects. Side effects are generally mild and may go away with time as the body adjusts to the use of naltrexone.

Common side effects of naltrexone include:

• stomach cramps
• difficulty sleeping
• anxiety
• nausea or vomiting
• headache
• low energy
• muscle, bone, or joint pain
• changes in mood

Serious side effects, although rare, can also occur. If you develop severe side effects such as confusion or hallucinations, contact your doctor right away.

Effects On Weight

Decreased appetite, diarrhea, and nausea are common side effects of naltrexone, which may result in weight loss while taking this medication.

Unlike methadone and buprenorphine, naltrexone is not associated with weight gain.

Read more about weight changes caused by naltrexone

Dream Changes

Vivid dreams and nightmares can occur while taking naltrexone, due to how naltrexone interacts with dopamine and serotonin, two chemicals in the brain.

Read more about how naltrexone can cause dream changes

Feelings Of Nausea

Naltrexone can cause nausea. This side effect may or may not fade with time.

If you continue to feel very nauseous while taking naltrexone, your doctor may be able to offer suggestions for how to help ease nausea while taking this medication.

Having Hallucinations

Seeing or hearing things that aren’t there (hallucinations) is a rare, but potential side effect while taking naltrexone.

When it does occur, it generally only lasts for a short time. However, this is considered a serious side effect, and should be reported to a doctor as soon as possible.

Read more about the potential for naltrexone to cause hallucinations

Sexual Side Effects

Naltrexone, like buprenorphine and methadone, can have effects on sexual function and the menstrual cycle when taken for opioid addiction.

Sexual side effects associated with naltrexone use include:

• erectile dysfunction
• early morning erections
• restoring menstruation
• reduced sexual desire

The likelihood of experiencing sexual side effects from naltrexone may depend on the dose taken, a person’s substance use history, and other factors.

Developing Mania

Research on the use of naltrexone in people with a substance use disorder and co-occurring bipolar disorder has shown mixed results.

People with bipolar disorder who take naltrexone may see a reduction in manic symptoms, or experience worsened symptoms of mania and depression.

Read more about how naltrexone can affect mania

Possible Liver Damage

Naltrexone use may cause worsened liver or kidney damage in people who already have impaired hepatic or renal function.

Signs of liver damage can include:

• yellowing of the eyes or skin (jaundice)
• stomach pain lasting for more than a few days
• dark urine
• chronic fatigue

If you have impaired liver function, or are experiencing signs of liver damage while taking naltrexone, contact your prescribing physician right away.

Effects Of Combining Naltrexone With Other Drugs

There are several types of substances, including alcohol and other opioids, that should be avoided while taking naltrexone due to the potential for a negative interaction.

Potential effects of combining naltrexone with other drugs:

• reduced drug effectiveness
• intoxication
• accidental opioid overdose

Before starting naltrexone, be sure to tell your doctor about any drugs, including prescription medications, you’re currently taking.

Read more about the effects of combining naltrexone with other drugs

Naltrexone Dosage

Naltrexone comes in a couple dosage strengths. Dosing for naltrexone is determined based on the formulation, the intended use, and prescribed frequency of use.

Common dosages include:

• tablet form: 50 mg naltrexone
• injection: 380 mg naltrexone
• implant: 200 mg naltrexone (not available in the U.S.)

Average Naltrexone Dose

The average dose of naltrexone differs depending on the form of naltrexone you are taking: naltrexone in pill/tablet form or the naltrexone injection (Vivitrol). The dose provided for individuals can vary according to personal factors, including duration of opioid/alcohol dependence and overall health.

Read more about the average dose of naltrexone

How Often Naltrexone Is Taken

Naltrexone for alcohol dependence (tablet form) is taken either once, daily, or three times a week. The injectable form of naltrexone (Vivitrol) is administered intramuscularly (into the muscle) once a month, typically in an outpatient setting.

Read more about how often you need to take naltrexone

How To Take Naltrexone

Naltrexone is taken in the form of an oral tablet or intramuscular injection. The tablet form of naltrexone is taken by mouth. This can be taken at home, with or without food. Eating prior to taking naltrexone may help prevent stomach upset. Naltrexone injections are injected into the muscle by a medication-assisted treatment (MAT) practitioner such as a nurse or doctor.

Read more about how to properly administer naltrexone

How Long Will You Be On Naltrexone?

Naltrexone can be prescribed as a long-term medication-assisted treatment (MAT) for opioid use disorder or alcohol dependence. How long naltrexone treatment lasts depends on each person’s individual treatment experience, including progress in treatment and the recommendation of their doctor.

Getting A Naltrexone Prescription

Naltrexone tablets for alcohol dependence can be prescribed by any healthcare practitioner that is licensed to prescribe medication. Administering Vivitrol (naltrexone injections) for opioid addiction, however, requires a Risk Evaluation Mitigation Strategy (REMS), which is a type of drug safety program.

Not all prescribing physicians may offer naltrexone injections. However, they may be able to offer a referral to a doctor or treatment center that does.

Read more about who can prescribe naltrexone

Is Naltrexone Right For Everyone?

Naltrexone isn’t necessarily the best fit for every person seeking treatment for opioid or alcohol use disorder. Because it requires full detox beforehand, it may be a better option for people who’ve already completed withdrawal or who have a strong support system to get through that process safely. People who prefer a non-opioid medication, or who are concerned about the potential for dependence with drugs like methadone or buprenorphine, often find naltrexone appealing for that exact reason.

A doctor can help evaluate factors like the severity of dependence, personal treatment goals, and any co-occurring health conditions to determine whether naltrexone, another medication, or a combination of approaches makes the most sense for an individual’s recovery.

Naltrexone FAQs

Find answers to frequently asked questions about naltrexone for opioid use disorder or alcohol use disorder.

❓ Can Naltrexone Help With Anxiety?

✔️ Anxiety is a common side effect of naltrexone. However, some research suggests it may also be helpful for decreasing anxiety in people with co-occurring anxiety disorders.

❓ What Happens If You Take Naltrexone With Opioids?

✔️ Naltrexone should not be taken until a person has fully detoxed. Taking naltrexone with opioids still in your system could cause precipitated withdrawal.

Taking very high doses of an opioid drug can also lead to accidental overdose, due to an inability to gauge the effects of opioids in the body and decreased opioid tolerance.

❓ Can You Get Drunk While Taking Naltrexone?

✔️ Drinking alcohol while taking naltrexone is not recommended. Naltrexone blocks the euphoric effects of alcohol (“the buzz”) but it doesn’t prevent impairment.

❓ How Much Does Naltrexone Cost?

✔️ The cost of naltrexone can vary depending on a wide range of factors.

This includes:

• drug formulation (i.e. tablet vs. injection)
• dosage
• brand name or generic version
• type of health insurance
• state of residence

The average cost of oral naltrexone is $25 to $60 a month. Naltrexone provided by an opioid treatment program may cost up to $1,1756 for a monthly injection and related support services.