Vivitrol is the brand name of an extended-release injectable form of naltrexone. It’s FDA-approved for the treatment of alcohol use disorder and opioid use disorder. Vivitrol blocks the euphoric effects of opioids by antagonizing opioid receptors; however, its effect on alcohol involves different mechanisms, such as modulation of the dopaminergic and endogenous opioid systems, rather than direct blockade of alcohol-induced euphoria.[1]

How Does Vivitrol Work?

Naltrexone blocks the euphoric and sedative effects of drugs such as heroin, morphine, and codeine.[2] It works differently in the body than buprenorphine and methadone, which activate opioid receptors in the body that suppress cravings.[3]

Naltrexone binds and blocks opioid receptors, reducing opioid cravings[4]. There is no misuse or abuse potential with naltrexone, because naltrexone is non-addictive.[5] Naltrexone does not produce euphoria but may affect mood in some individuals, including rare reports of depression or dysphoria.

If a person relapses and uses alcohol or an opioid drug, naltrexone prevents the feeling of euphoria associated with getting high.[6] Naltrexone significantly reduces the pleasurable effects of opioids and alcohol, but may not completely eliminate them in all users.

That said, people using naltrexone should not use any opioids, alcohol, or illicit drugs.

How is Vivitrol Administered?

Vivitrol is given as a single intramuscular injection once a month by your healthcare provider.[7] Vivitrol is designed to reduce cravings and prevent relapse in people recovering from alcohol use disorder and opioid use disorder.

Vivitrol reduces cravings and prevents relapse in individuals who are recovering from alcohol use disorder and opioid use disorder.[8] Unlike some other medications used in addiction treatment, Vivitrol is non-addictive and does not contain any opioids. Its extended-release nature means that the active ingredient, naltrexone, is slowly released into the body over a period of a month, providing ongoing therapeutic effects.

What Are The Side Effects of Vivitrol?

While Vivitrol is generally well-tolerated, adverse side effects can occur.[9] Most are mild and resolve on their own. A few are more serious and require medical attention. As with all medications, individual responses to Vivitrol vary.

Most Common Side Effects of Vivitrol

The side effects of Vivitrol typically occur during the initial stages of treatment. These are generally mild to moderate and diminish over time as the body adjusts.

Some of the most frequently reported common side effects include:[10]

• Nausea, vomiting, and diarrhea. Gastrointestinal upset is frequently reported.
• Headache. Mild to moderate headaches are common.
• Fatigue or tiredness. Some individuals may feel unusually tired.
• Dizziness. Temporary dizziness can occur, especially after the first dose.
• Insomnia. Trouble going to sleep or staying asleep
• Decreased appetite
• Joint pain
• Muscle cramps or muscle aches
• Cold-like symptoms. Symptoms similar to a common cold, such as sneezing or a runny nose.
• Injection site reactions. These are among the most common adverse effects due to the vivitrol injection. Patients may experience pain, tenderness, swelling, redness, or bruising in the affected area. Itching or a hard lump at the site of the intramuscular injection is not unusual.

Serious Side Effects of Vivitrol

Vivitrol is considered a safe and effective treatment for opioid use disorder (OUD) and alcohol use disorder (AUD). However, while most side effects of Vivitrol are mild, some can be severe.[11]

If any severe side effects of Vivitrol occur, they will require immediate medical attention.

These include:

• Liver damage or liver problems. Although rare, Vivitrol can cause liver damage or hepatitis.[12] Symptoms of liver problems can include severe stomach pain, unusual tiredness, yellowing of the skin or the whites of the eyes, or dark urine.
• Serious allergic reactions. Some individuals may experience a life-threatening allergic reaction.[13] Signs include a skin rash, hives, swelling of the face, eyes, lips, tongue, or throat, trouble breathing or swallowing, and severe dizziness or fainting. These reactions require immediate emergency medical help.
• Sudden opioid withdrawal. If Vivitrol is administered to a patient who has not completely detoxified from opioids, it can bring on sudden opioid withdrawal.[14] This is a rapid and intense onset of withdrawal symptoms, including severe stomach cramps, muscle aches, diarrhea, nausea, vomiting, fast heart rate, fever, sweating, and intense cravings. This is why it is a must for patients to be opioid-free for a minimum of 7 to 14 days before starting Vivitrol.[15]

Who Is Most at Risk for Vivitrol Side Effects?

Although most people tolerate Vivitrol well, some populations experience higher risks. These include:

• Patients who have recently used opioids: Taking Vivitrol without completing detox can trigger sudden withdrawal.[16]
• Individuals with a history of allergic reactions to naltrexone.
• Individuals with respiratory conditions may be at a higher risk of complications if they develop eosinophilic pneumonia.

Managing Vivitrol Side Effects at Home

While serious complications are rare, many people experience mild side effects that can be managed at home. Here are a few practical tips:

• Get plenty of fluids. Fatigue and dizziness can sometimes be caused by dehydration.
• Use a warm compress on the injection site. This may help alleviate swelling and tenderness.
• Pain relievers. With a doctor’s guidance, acetaminophen or ibuprofen can be used for headaches, joint pain, or muscle cramps.
• Get sufficient rest. A good night’s sleep supports recovery and helps manage tiredness or flu-like symptoms.
• Avoid alcohol or sedatives. Alcohol will interfere with naltrexone’s action and increase side effect severity.

Patients should always notify their healthcare provider before taking any new over-the-counter or prescription medication while on Vivitrol. If you are experiencing serious side effects, contact your doctor immediately.

Risks of Missing a Dose of Vivitrol

Vivitrol must be administered monthly to maintain its therapeutic benefits. Missing a scheduled injection can:

• Increase the risk of relapse, especially in early recovery.
• Reduce consistency in craving suppression.
• Require re-evaluation, including possible detox, if opioids have been used again.

If more than a few days have passed since a missed dose, a patient should consult their healthcare provider for the safest course of action forward. [17]

Managing Vivitrol Side Effects: Long-Term Outlook

For many patients, side effects diminish within the first few months. With each injection, the body becomes more accustomed to the medication. Over time, people report fewer cravings, less anxiety about relapse, and improved confidence in their recovery.

If you or someone you know is living with substance misuse, there is hope and healing. With full-spectrum treatment that includes professional therapy, support groups, and compassionate care, enduring recovery is possible.