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Naltrexone Shot (Vivitrol): Dosages, Administration, and More

Naltrexone Shot (Vivitrol): Dosages, Administration, and More

The naltrexone shot (Vivitrol) offers convenient once-monthly treatment to minimize opioid and alcohol cravings with low risk for addiction or overdose.

Vivitrol, the brand name for the naltrexone shot, is an FDA-approved medication for treating opioid use disorder (OUD) and alcohol use disorder (AUD). This injectable version of naltrexone makes treatment more convenient as it is delivered as a once-monthly shot instead of daily tablets. Whether you are interested in oral or injectable naltrexone treatment, you should always access your medication from a qualified provider and a licensed pharmacy.

If you need help managing opioid or alcohol cravings, you may be a good candidate for oral naltrexone treatment through Confidant Health. Our online medication-assisted treatment allows you to receive support for OUD and AUD from the comfort of home. We offer oral naltrexone and Suboxone care through our online Suboxone clinic but can help you find a local provider if monthly injectable treatment is more suitable for you. Reach out to us today to schedule a virtual assessment.

What Is a Naltrexone Shot (Vivitrol)?

Naltrexone is prescribed to reduce cravings in people trying to overcome opioid or alcohol use disorder. The medication is offered in two forms: tablets and injections. A naltrexone shot or injection (XR-NTX) is delivered as a monthly extended-release intramuscular shot. If you are prescribed injectable naltrexone, you will need to visit your provider once a month to receive your medication.

How Does a Naltrexone Shot (Vivitrol) Work?

Naltrexone is an opioid antagonist that binds to opioid receptors and blocks other opioids from interacting with these receptors and making you feel high. A naltrexone shot works by slowly releasing the medication over 28 days. The effects peak two hours after administration and again two days later. Although the peak is soon after administration, the opioid-blocking effects of the naltrexone shot will continue to work for one month.

Naltrexone Shot (Vivitrol) Prescription

The naltrexone shot (Vivitrol) is offered in one strength: a 380 mg injection. You receive the shot once a month in your provider's office. For many people, this provides the most convenient form of support for opioid and alcohol use disorder.

Naltrexone Shot (Vivitrol) Dosage and Administration

The 380 mg injection is the only dosage of naltrexone available. Your provider will administer the Naltrexone shot in their office once per month. 

Naltrexone Shot (Vivitrol) Uses

The primary purpose of the naltrexone shot is to minimize cravings for opioids or alcohol. Naltrexone binds to opioid receptors in the brain and prevents other opioids from attaching to these receptors. This blocks other opioids from inducing euphoria, lessening the motivation to use these substances. 

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Naltrexone Shot (Vivitrol) Safety and Precautions

Although naltrexone blocks the effects of opioids, it does not produce feelings of euphoria like some other OUD medications. Since it does not induce euphoria, the risk of addiction is minimal to none. However, there are some precautions you must take to ensure your safety when accessing naltrexone treatment.

You should discontinue opioids seven to 14 days before beginning naltrexone treatment.

Starting a naltrexone regimen while experiencing opioid withdrawal symptoms can instigate precipitated withdrawal. Precipitated withdrawal is an abrupt type of withdrawal that occurs when using certain medications for substance use disorder. Symptoms may include nausea, vomiting, headaches, diarrhea, and chills. To prevent precipitated withdrawal, you should be honest with your provider about your last consumption of opioids to determine when it is safe to start your naltrexone treatment. If you're struggling with abstinence, your provider may recommend an alternative course of treatment to help you manage withdrawal symptoms before considering a naltrexone regimen.

There is a risk of overdose while receiving naltrexone treatment.

Although naltrexone is unlikely to be addictive, you can still overdose when receiving this medication. The risk of overdose is often caused by trying to overpower the opioid-blocking effects of naltrexone with high doses of opioids or alcohol. When accessing naltrexone care for OUD or AUD, it is crucial that you avoid consuming large quantities of these substances. 

The risk of overdose may increase after discontinuing naltrexone treatment.

The opioid-blocking effects of naltrexone will eventually decrease your tolerance to opioids. You may inadvertently overdose if you discontinue naltrexone treatment and resume your previous opioid dosage with lowered tolerance. If you experience intense urges to resume opioid use during or after naltrexone treatment, reach out to your provider right away for support.

Naltrexone treatment may not be recommended if you have compromised liver function.

Naltrexone is metabolized through the liver, so if you have compromised liver function, you could experience more severe liver damage from the medication. Naltrexone can also lead to liver damage or hepatitis, so you should consult your provider if you show symptoms such as darkened urine, chronic stomach pain, or yellowing of the whites of your eyes. 

The naltrexone injection presents a potential for additional side effects.

Oral and injectable naltrexone both have the risk of side effects, but since Vivitrol is injected, a few additional side effects may occur. You might have pain, redness, swelling, itching, or burning at the injection site. If you have an intolerance to the naltrexone injection, you should contact your provider immediately to determine how to proceed with treatment. If you have a reaction to the naltrexone injection, you may still be a candidate for oral naltrexone treatment.

Naltrexone Shot (Vivitrol) Drug Interactions

To maintain the safety and efficacy of your naltrexone treatment, you should be aware of potential drug interactions. 

OUD Medications 

OUD medications that are classified as opioids do not mix well with naltrexone. Buprenorphine is a partial opioid agonist that creates mild euphoria. Methadone, a full opioid agonist, also produces pleasurable feelings. Adding an opioid antagonist medication like naltrexone to a partial or full opioid agonist can result in precipitated withdrawal.

Opioid Medications

Naltrexone will block the effects of opioid medications like codeine, hydrocodone, and oxycodone, rendering them ineffective. This could lead you to take more of the medication than prescribed to achieve the desired effects, which increases the risk of overdose.

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Naltrexone Shot (Vivitrol) FAQs

What other drugs will affect naltrexone?

Naltrexone will block the effects of opioid medications. If you are prescribed opioids for the treatment of opioid use disorder, pain, chronic cough, or diarrhea, you should notify your provider before beginning a naltrexone regimen. They may need to select an alternative medication for your treatment.

Opioid medications can override the opioid-blocking effects of naltrexone when consumed in large doses. This presents the highest risk of overdose with naltrexone treatment.

Some examples of opioid medications that interact with naltrexone are buprenorphine, codeine, fentanyl, hydrocodone, morphine, methadone, and tramadol.

Does the Vivitrol shot work immediately?

The Vivitrol shot will begin to block opioids within an hour of administration, with effects peaking at the two-hour mark and again two to three days later.

Does the Vivitrol shot make you sick? 

The Vivitrol shot won't make you sick unless you have an adverse reaction, experience side effects, or receive the injection before you have completed opioid or alcohol withdrawal. Some people may have an allergic reaction to the medication and experience symptoms like rash, chest pain, dizziness, and difficulty breathing. Vivitrol can also lead to side effects like nausea, vomiting, muscle cramps, insomnia, or cold symptoms. If taken too soon after the last dose of opioids or alcohol, you can experience precipitated withdrawal symptoms.

Does Vivitrol work instantly?

Although Vivitrol does not work instantly, it will begin to block the effects of opioids within the first hour after your injection.

What should I do if I forget a dose?

It is much less likely that you will forget a dose of naltrexone when you receive a once-monthly injection. If you miss your appointment for your naltrexone shot, you should call your provider promptly to reschedule. Waiting too long between injections can lead to opioid and alcohol cravings, which can derail your recovery progress. It can also make you more vulnerable to overdose on lower amounts of opioids due to a decreased tolerance.

How long does Vivitrol last?

As an extended-release naltrexone injection, Vivitrol continues to block the effects of opioids for approximately 28 days. 

Get Online Naltrexone Care from Confidant Health

Online medication-assisted treatment is an excellent way to fit OUD and AUD treatment into a busy schedule. The professionals at Confidant Health are here to help you achieve your goals of cutting alcohol or opioids out of your life with virtual naltrexone or Suboxone treatment. Schedule an online assessment today to get started on your recovery path.

This article has been medically reviewed by
Erin Hillers
Erin Hillers
Erin Hillers
Nurse Practitioner

Erin is a Nurse Practitioner with 8 years of experience in midwifery and women's health. She has spent the past 5 years specializing in the treatment of opioid and alcohol use disorders.

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