Naltrexone and Vivitrol Treatment Centers

Naltrexone is an opioid antagonist, meaning it binds to the mu-opioid receptors in the brain without activating them. By occupying these receptors, naltrexone effectively blocks the rewarding effects of opioids and reduces the neurochemical reinforcement that drives alcohol cravings. Unlike medications such as methadone or buprenorphine, naltrexone has no potential for abuse or physical dependence because it produces no opioid effect whatsoever.

How Naltrexone Works

When a person taking naltrexone consumes alcohol, the pleasurable dopamine surge that normally reinforces drinking behavior is significantly blunted. For individuals with opioid dependence, naltrexone prevents any ingested opioid from reaching the receptors, rendering opioid use ineffective. This pharmacological mechanism makes naltrexone a cornerstone of medication-assisted treatment (MAT) programs across the country. Naltrexone was first approved by the FDA in 1984 for opioid dependence and received additional approval for alcohol dependence in 1994.

Naltrexone Side Effects

Common side effects include:

• Nausea, especially during the first few days
• Headache and dizziness
• Fatigue and insomnia
• Joint and muscle pain
• Decreased appetite and anxiety

Serious side effects are less common but include signs of liver injury such as yellowing of the skin or eyes, dark urine, and persistent abdominal pain. Severe injection site reactions from Vivitrol, including tissue necrosis, have been reported in rare cases. Importantly, naltrexone lowers opioid tolerance over time — if a person discontinues naltrexone and attempts to use opioids at previously tolerated doses, the risk of fatal overdose increases significantly.

Naltrexone for Alcohol Dependence

Naltrexone is one of only three FDA-approved medications for alcohol use disorder, alongside disulfiram (Antabuse) and acamprosate (Campral). For individuals struggling with alcohol dependence, naltrexone reduces heavy drinking days and increases the percentage of days abstinent. The oral formulation, sold under the brand name Revia, is typically prescribed at 50 mg daily and is most effective when combined with behavioral therapy and support groups.

Naltrexone for Opioid Dependence

For opioid dependence, naltrexone serves as a relapse-prevention tool rather than a detox medication. Patients must complete a full opioid detoxification and remain opioid-free for a minimum of 7 to 14 days before beginning naltrexone therapy. Starting naltrexone while opioids are still present can trigger sudden and severe precipitated withdrawal. Once initiated, naltrexone provides a pharmacological safety net — if a patient relapses, naltrexone blocks the drug from producing its usual effects.

Vivitrol: Injectable Naltrexone

Vivitrol is the brand name for naltrexone extended-release injectable suspension, delivering 380 mg in a single intramuscular dose once per month. A healthcare provider injects Vivitrol into the gluteal muscle using a special needle included in the product kit, alternating sides each month. The Vivitrol shot has become increasingly popular because it solves one of the biggest challenges in addiction treatment: medication adherence. Studies show that patients receiving monthly Vivitrol injections are significantly more likely to remain in treatment compared to those prescribed daily oral naltrexone.

Vivitrol Side Effects

Vivitrol shares many side effects with oral naltrexone but carries additional risks related to the injection site. These range from mild tenderness, redness, and swelling to severe complications including induration and in rare cases tissue necrosis requiring surgical intervention. As with oral naltrexone, Vivitrol can affect liver function, and depressed mood and suicidal thoughts have also been reported.

Revia: Oral Naltrexone Brand

Revia is the primary brand name for oral naltrexone hydrochloride tablets in a 50 mg strength. Today, most prescriptions are filled with generic naltrexone, which is bioequivalent and significantly less expensive. The main advantage of oral naltrexone over injectable Vivitrol is lower cost and greater dosing flexibility, but it requires daily compliance, which patients in early recovery frequently struggle with.

Low Dose Naltrexone (LDN)

Low dose naltrexone (LDN) refers to naltrexone prescribed at doses ranging from 0.5 mg to 5 mg — a fraction of the standard 50 mg addiction treatment dose. LDN is used off-label and is not FDA-approved for any condition at these low doses. It is not a treatment for addiction and operates through a fundamentally different mechanism. The theory proposes that a brief, transient blockade of opioid receptors causes a rebound effect that increases the body's natural endorphin production. LDN has been investigated for conditions including fibromyalgia, multiple sclerosis, and Crohn's disease, but large-scale clinical trials are still needed.

Naltrexone Cost and Insurance

Generic oral naltrexone typically costs $30 to $80 per month without insurance. With insurance or discount programs, out-of-pocket cost can fall below $15. Vivitrol injections cost $1,000 to $1,800 without insurance, but most private plans, Medicaid, and Medicare cover it. Alkermes offers the Vivitrol Co-Pay Savings Program for insured patients and a Patient Assistance Program for those without insurance.

Naltrexone Dosage

The standard oral dose is 50 mg once daily, with some providers starting at 25 mg for the first day to minimize side effects. For Vivitrol, the dose is 380 mg as a single intramuscular injection every four weeks. Patients must be opioid-free for a minimum of 7 to 14 days before initiating either formulation.

Naltrexone vs Naloxone: What's the Difference?

Both are opioid antagonists, but they differ in duration and use. Naloxone (Narcan) is a short-acting emergency overdose reversal agent that takes effect within minutes and wears off in 30 to 90 minutes. Naltrexone is a long-acting antagonist for ongoing relapse prevention, providing blockade for 24 hours (oral) or 30 days (Vivitrol). Naloxone is also a component of Suboxone, where it deters injection misuse.

Naltrexone vs Suboxone

Suboxone contains buprenorphine (a partial opioid agonist) that mildly stimulates opioid receptors, reducing cravings and withdrawal. Naltrexone fully blocks receptors with zero agonist activity. Patients must be fully detoxed before starting naltrexone, whereas Suboxone can be initiated during early withdrawal. A landmark 2017 clinical trial (X:BOT) found that among patients who successfully started treatment, relapse rates were similar between Vivitrol and Suboxone.

Naltrexone and Weight Loss

Naltrexone is one of two active ingredients in Contrave (naltrexone/bupropion), an FDA-approved weight management medication. However, naltrexone alone is not approved for weight loss. Some patients undergoing addiction treatment report modest weight changes related to reduced alcohol calories or appetite-suppressing side effects, but naltrexone should not be selected as an addiction medication primarily for weight effects.

Naltrexone resources:

• SAMHSA — Medications for Substance Use Disorders
• NIDA — Medications to Treat Opioid Addiction