What is Naltrexone (Intramuscular Route): Uses, Dosage, Side Effects and More

Naltrexone intramuscular injection is a monthly shot that helps people stay sober from alcohol or opioids. This medication works by blocking the rewarding effects of these substances in your brain, making it easier to maintain your recovery.

Think of it as a protective shield that lasts for about a month. When you receive this injection, you're taking a significant step toward long-term recovery with the support of medical professionals who understand your journey.

What is Naltrexone Intramuscular Injection?

Naltrexone intramuscular injection is a long-acting form of naltrexone that's given as a shot into your muscle once a month. Unlike daily pills, this injection provides steady medication levels in your body for approximately 30 days.

The medication is administered by a healthcare provider in a clinical setting. This ensures you receive the right dose and proper medical supervision throughout your treatment.

The injection site is typically your buttock muscle, where the medication is slowly released over time. This steady release helps maintain consistent protection against alcohol and opioid effects.

What is Naltrexone Used For?

Naltrexone intramuscular injection primarily treats alcohol use disorder and opioid use disorder in adults. It's specifically designed for people who are already sober and want to maintain their recovery.

For alcohol use disorder, this medication helps reduce cravings and makes drinking less rewarding. Many people find it easier to stick to their sobriety goals when they have this monthly support.

When treating opioid use disorder, naltrexone blocks the euphoric effects of opioids like heroin, prescription painkillers, and fentanyl. However, you must be completely free from opioids for at least 7-10 days before starting treatment.

Your doctor might also consider this medication if you've had trouble remembering to take daily naltrexone pills. The monthly injection removes the daily decision-making around medication compliance.

How Does Naltrexone Work?

Naltrexone works by blocking opioid receptors in your brain, which are the same receptors that alcohol and opioids target to create their rewarding effects. This makes it a moderately strong medication that provides reliable protection.

When you drink alcohol or use opioids while on naltrexone, you won't experience the usual pleasant feelings. Instead, these substances essentially become ineffective at producing euphoria or relaxation.

The medication doesn't make you feel sick or unwell when you encounter these substances. It simply removes the rewarding experience that typically drives continued use.

This blocking effect lasts for the entire month between injections. Your brain's opioid receptors remain occupied by naltrexone, providing consistent protection even if you have moments of weakness or strong cravings.

How Should I Take Naltrexone Intramuscular Injection?

You'll receive your naltrexone injection at your doctor's office or clinic once every four weeks. The healthcare provider will give you the shot in your buttock muscle, alternating sides with each injection.

Before your appointment, you can eat normally and don't need to avoid any specific foods. However, wearing loose-fitting clothing can make the injection process more comfortable.

The injection itself takes just a few minutes, though you might need to stay for a brief observation period. Some clinics like to monitor patients for 15-30 minutes after the injection to ensure no immediate reactions occur.

You'll need to schedule your next appointment before leaving the clinic. Keeping a consistent monthly schedule helps maintain steady medication levels in your system.

How Long Should I Take Naltrexone For?

Most people continue naltrexone injections for at least 6-12 months, though some benefit from longer treatment periods. Your doctor will work with you to determine the right duration based on your individual recovery progress.

The length of treatment often depends on your personal circumstances, support system, and how well you're managing your recovery. Some people find they need ongoing support for several years, while others may transition to other forms of treatment.

Your healthcare provider will regularly assess your progress and discuss whether continuing treatment makes sense for your situation. These conversations typically happen every few months during your routine appointments.

Remember that stopping naltrexone should always be a planned decision made with your doctor's guidance. Suddenly discontinuing treatment can leave you vulnerable to relapse without proper support systems in place.

What Are the Side Effects of Naltrexone?

Most people tolerate naltrexone injections well, but you might experience some side effects, especially in the first few weeks. These effects are generally manageable and often improve as your body adjusts to the medication.

Here are the most common side effects you might notice:

• Injection site reactions like pain, swelling, or redness
• Nausea or stomach upset
• Headaches
• Dizziness or fatigue
• Trouble sleeping
• Decreased appetite
• Muscle or joint pain

These common side effects typically last a few days to a week after each injection. Most people find them tolerable and manageable with simple comfort measures.

Less common but more serious side effects can occasionally occur, and you should contact your doctor if you experience any concerning symptoms:

• Severe injection site reactions with increasing pain or warmth
• Signs of depression or mood changes
• Severe nausea or vomiting
• Unusual tiredness or weakness
• Abdominal pain or discomfort

Rare but serious side effects include liver problems, though this is uncommon with the injection form. Your doctor will monitor your liver function through periodic blood tests.

Very rarely, some people develop severe allergic reactions to naltrexone. Signs include difficulty breathing, swelling of face or throat, or widespread rash. This requires immediate medical attention.

Who Should Not Take Naltrexone?

Naltrexone isn't safe for everyone, and certain conditions make this medication inappropriate or potentially dangerous. Your doctor will carefully review your medical history before prescribing this treatment.

You should not receive naltrexone injections if you:

• Are currently using opioids or haven't been opioid-free for at least 7-10 days
• Have severe liver disease or liver failure
• Are allergic to naltrexone or any ingredients in the injection
• Are pregnant or breastfeeding
• Have severe kidney disease

Your doctor will also use extra caution if you have certain health conditions that require careful monitoring during treatment.

People with mild liver problems might still be candidates for treatment, but they'll need more frequent monitoring through blood tests. Your doctor will weigh the benefits against the risks in these situations.

If you're taking prescription opioid medications for pain management, you'll need to work with your doctors to develop an alternative pain management plan before starting naltrexone.

Naltrexone Brand Names

The most common brand name for naltrexone intramuscular injection is Vivitrol. This is the version most doctors prescribe and insurance companies typically cover.

Vivitrol contains 380 mg of naltrexone in each monthly injection. The medication comes as a powder that your healthcare provider mixes with a special liquid right before giving you the shot.

Some compounding pharmacies may prepare other forms of long-acting naltrexone, but Vivitrol remains the most widely studied and prescribed option. Your doctor will likely start with this well-established formulation.

Naltrexone Alternatives

Several other medications can help with alcohol or opioid use disorder if naltrexone isn't right for you. Your doctor can discuss these options based on your specific needs and circumstances.

For alcohol use disorder, alternatives include acamprosate, which helps reduce cravings, and disulfiram, which causes unpleasant reactions when you drink. Some people also benefit from topiramate or gabapentin.

For opioid use disorder, buprenorphine and methadone are effective alternatives. These medications work differently than naltrexone by partially activating opioid receptors rather than blocking them completely.

Some people do better with daily oral naltrexone if they prefer not to get monthly injections. Others might benefit from combination approaches that include counseling, support groups, and lifestyle changes.

Is Naltrexone Better Than Buprenorphine?

Both naltrexone and buprenorphine are effective for treating opioid use disorder, but they work in different ways and suit different people. Neither medication is universally "better" than the other.

Naltrexone completely blocks opioid effects, which some people prefer because it doesn't cause physical dependence. However, you must be completely opioid-free before starting treatment, which can be challenging.

Buprenorphine partially activates opioid receptors, which helps manage withdrawal symptoms and cravings while blocking the effects of other opioids. You can start this medication while still experiencing withdrawal, making the transition easier.

Your doctor will help you choose based on your individual situation, including how long you've been sober, your support system, and your personal preferences about treatment approaches.