Opioid Blocker Shot: How Injections Work for Opioid Use Disorder

Recovery from opioid use disorder (OUD) looks different for everyone. Having the right tools can make your journey easier. One treatment option is a long-acting injection, often called an opioid blocker shot. The medication used for this shot is extended-release injectable naltrexone, sold under the brand name Vivitrol. This treatment helps to block the effect of opioids in the brain so they don’t produce feelings of euphoria (a “high”).

Thanks! You've successfully submitted your vote.

Sign up to view the results!

Continue with Facebook

Sign up with your email

By joining, you accept our Terms of Use, and acknowledge our collection, sharing, and use of your data in accordance with our Health Data and Privacy policies.

Already a Member? Log in

Understanding how this medication works, what to expect during treatment, and possible side effects can help you and your doctor decide if it may be a good fit for your recovery plan.

What Is an Opioid Blocker Shot?

The opioid blocker shot is a long-acting naltrexone injection. Naltrexone belongs to a group of drugs called medications for opioid use disorder (MOUD). Other types of MOUD include buprenorphine and methadone. All types of MOUD are approved by the U.S. Food and Drug Administration (FDA) to treat OUD.

Naltrexone is also available as a pill you have to take every day. However, many people find it difficult to stick to this treatment plan. Additionally, the pill form isn’t typically recommended for people with OUD. The long-acting injection form of naltrexone is FDA-approved to prevent relapse to opioid dependence after detoxification (detox) and to treat alcohol dependence in people who are able to abstain before starting treatment. The injection is intended to be part of a comprehensive treatment plan that includes counseling and behavioral health therapy.

How Does Naltrexone Work?

Naltrexone works differently from other medications for OUD because it’s not an opioid drug. Instead, naltrexone is an opioid antagonist. It works by blocking opioid receptors in the brain. That’s why it’s also known as an “opioid blocker.”

When opioids attach to opioid receptors and activate them, they produce effects like pain relief, euphoria, and drowsiness. Naltrexone binds to opioid receptors without activating them. In doing so, it blocks the pleasurable effect of other opioids such as heroin, morphine, or oxycodone. Naltrexone may also help reduce opioid cravings.

Other Injections for Opioid Use Disorder

Naltrexone is the only available opioid blocker injection. However, buprenorphine is another type of MOUD available as a long-acting injection, sold under brand names including Brixadi and Sublocade. The injectable form of buprenorphine is given once a week or once a month to provide a steady dose of medication without the need for daily pills or films.

Unlike naltrexone, buprenorphine is a partial opioid agonist (activator). Buprenorphine is an opioid drug that works by binding to opioid receptors and activating them just enough to reduce cravings and withdrawal symptoms, but not enough to cause a strong high.

How Do You Get the Naltrexone Injection for OUD?

You can get a prescription for naltrexone injection from any healthcare provider, even if they aren’t part of an opioid treatment program (OTP). Starting naltrexone injection for OUD involves a few important steps. Knowing what to expect can help you feel more prepared and confident as you begin this part of your recovery.

Opioid Detoxification

Before starting naltrexone, a person must stop taking all opioids for at least seven to 10 days. Someone taking a long-acting opioid, like methadone, may need to wait up to 14 days before their first injection. Starting naltrexone without detoxification can cause sudden withdrawal symptoms that are uncomfortable and potentially dangerous.

It’s important to talk to your healthcare provider about your recent opioid use before starting to avoid serious withdrawal symptoms. You shouldn’t get the naltrexone injection if you currently have an opioid dependence or are experiencing withdrawal symptoms.

Receiving the Injection

The naltrexone injection is given once a month at a healthcare provider’s office or clinic. It’s given as an intramuscular (in the muscle) injection into the muscle of your buttocks. You’ll alternate the side where you get the monthly injection.

After the first injection, it may take two to three days to reach its full effect. For most people, one naltrexone injection will last for four weeks. However, some people who process the medication quickly may need an injection once every three weeks.

Access and Cost

Naltrexone isn’t classified as a controlled substance by the Drug Enforcement Administration (DEA), so any healthcare provider with the authority to prescribe medications can write a prescription for a naltrexone injection.

On the other hand, buprenorphine and methadone are controlled substances that must be prescribed by healthcare providers who are registered with the DEA or part of an OTP.

Insurance coverage for the naltrexone injection varies among plans. According to the manufacturer of Vivitrol, the drug is covered by most insurance plans, and many people have low copays. Additionally, some community health centers may offer naltrexone injection at reduced or no cost.

What Are the Risks of Naltrexone Injection?

Naltrexone injection is safe and effective for most people, but it’s important to understand the potential risks of this treatment option. Like all medications, naltrexone injection can cause side effects. Additionally, naltrexone treatment can increase your sensitivity to opioids and increase your risk of overdose.

Naltrexone Injection Side Effects

Nausea is a common side effect that many people experience after the first naltrexone injection. For most people, nausea improves within a few days and is less likely to occur with future naltrexone injections. Other common side effects of naltrexone injection include:

• Drowsiness or sleepiness
• Headache
• Vomiting
• Dizziness or lightheadedness
• Loss of appetite
• Joint or muscle pain
• Symptoms similar to a cold
• Difficulty sleeping
• Toothache

Less commonly, naltrexone injection can cause serious side effects, such as:

• Severe injection-site reactions, including pain, swelling, tissue death, or open wounds
• Liver problems
• Severe allergic reactions
• Pneumonia
• Depression or suicidal thoughts

Note: If you or someone you know needs help, you can contact the 988 Suicide & Crisis Lifeline by calling or texting 988 or chatting online.

Risk of Opioid Overdose

Accidental overdose is one of the most serious risks of a naltrexone injection. There are two main methods of taking naltrexone injection that can increase this risk.

First, some people try to take large amounts of opioids to overcome the blocking effect of naltrexone. Doing this is very dangerous and can lead to injury, coma, or death.

Second, when the medication wears off, a person’s body can become more sensitive to opioids. When this happens, even a small dose of opioids can lead to overdose.

While receiving naltrexone injections, it’s important to let your friends and family members know about the increased risk of overdose. You should also ask your healthcare provider about naloxone for emergency treatment of opioid overdose, and make sure your loved ones know what to do if an overdose occurs.

What Are the Benefits of Naltrexone Injection?

The naltrexone injection can be a useful tool to help people with OUD avoid returning to opioid use. In clinical trials, significantly more people taking naltrexone injection for six months were able to remain opioid-free compared to those taking a placebo (inactive treatment).

Naltrexone has additional advantages over other types of MOUD. Unlike methadone and buprenorphine, which can cause opioid dependence, naltrexone isn’t addictive because it isn’t an opioid medication. That also means there isn’t a risk of opioid withdrawal from stopping naltrexone.

Naltrexone injection may be a good treatment option if you:

• Don’t want to take medication every day
• Haven’t had successful treatment with other types of MOUD
• Have a less severe OUD
• Are highly motivated to stop using opioids
• Can’t or prefer not to take opioid medications
• Have a high risk of relapse

Your healthcare provider can help you weigh the risks and benefits of OUD treatment with naltrexone injection compared to other treatment options.

Join the Conversation

On MyOpioidRecoveryTeam, people share their experiences with opioid use disorder, get advice, and find support from others who understand.

If you’ve taken an opioid blocker shot, how did it work for you? Let others know in the comments below.