Generic name: Naltrexone 
Brand name: Vivitrol 
Dosage form: Extended-release intramuscular injection, oral tablet 
Drug classes: Antidotes


Naltrexone, a stalwart in addiction treatment, is the hope for individuals grappling with opioid and alcohol dependence. It is essential to understand the multifaceted aspects of naltrexone, delving into its benefits, uses, dosing intricacies, potential side effects, precautions, and much more.

What is Naltrexone?

Naltrexone, a pharmacological agent classified as an opioid receptor antagonist, operates by binding to opioid receptors in the brain, effectively blocking the pleasurable effects of opioids and alcohol. This mechanism makes it a cornerstone in addiction treatment, aiding individuals in their journey toward recovery.

Benefits of Naltrexone

  1. Reduced Cravings: The hallmark of naltrexone's efficacy lies in its ability to diminish the overwhelming craving for opioids and alcohol. By blunting the reward pathways in the brain, it empowers individuals to resist the pull of addiction.
  2. Prevention of Relapse: Naltrexone acts as a formidable barrier against relapse by nullifying the euphoric effects of opioids. This fortification becomes particularly crucial during the early stages of recovery when vulnerability to relapse is high.
  3. Improved Treatment Outcomes: Incorporating naltrexone into addiction treatment plans has enhanced overall treatment effectiveness. By addressing both the physiological and psychological aspects of addiction, it contributes to a more holistic recovery process.

Uses of Naltrexone

Naltrexone is a linchpin in the management of opioid addiction. It is initiated once an individual is opioid-free for 7-10 days to prevent precipitated withdrawal. The medication serves as a steadfast ally, supporting individuals in maintaining abstinence and gradually reclaiming their lives from the clutches of addiction.

Beyond its role in opioid addiction, naltrexone has proven efficacy in curbing alcohol dependence. It does so by reducing the urge to drink, providing a crucial tool for those striving to break free from the cycle of alcohol abuse.

Side Effects of Naltrexone

  1. Nausea: A prevalent side effect that may occur initially but often subsides over time.
  2. Headache: Mild to moderate headaches can be experienced, though generally transient.
  3. Fatigue: Some individuals may report feelings of tiredness or lethargy.
  4. Dizziness: A common side effect that may occur, especially during the initial treatment.
  5. Liver Problems: Naltrexone may lead to liver-related issues. Immediate medical attention is warranted if symptoms such as yellowing of the eyes or skin, dark urine, or persistent nausea arise.

How to Take Naltrexone

Oral naltrexone is typically administered once daily. It can be taken with or without food, allowing individuals to incorporate it into their daily routine. Healthcare providers often initiate treatment with a low dose, gradually titrating upwards based on individual response.

The injectable form of naltrexone is administered monthly as an extended-release injection. This mode of delivery ensures consistent and sustained therapeutic levels, eliminating the need for daily adherence. Healthcare professionals usually handle the administration of the injectable form.

Accurate Dosing Information

Accurate dosing is paramount to the success of naltrexone treatment. Healthcare providers tailor the dosage based on individual needs, closely monitoring responses to optimize effectiveness while minimizing side effects. Regular follow-ups with healthcare professionals facilitate this fine-tuning process.


  1. Liver Conditions: Individuals with pre-existing liver conditions should inform their healthcare provider. Periodic liver function monitoring is crucial to mitigate the risk of liver-related complications.
  2. Medication Interactions: Full disclosure of all medications, including over-the-counter and herbal supplements, is imperative.

Who Should Not Use Naltrexone?

  1. Recent Opioid Use: Naltrexone should not be initiated until an individual has been opioid-free for 7-10 days to prevent precipitated withdrawal.
  2. Acute Hepatitis or Liver Failure: Pre-existing liver conditions warrant careful consideration, and naltrexone may not be suitable for individuals with acute hepatitis or liver failure.

What Happens During a Dose Miss?

Adherence to the prescribed dosing schedule is crucial for the effectiveness of naltrexone. If a dose is missed, it should be taken as soon as remembered. However, if the next scheduled dose is imminent, skipping the missed dose and resuming the regular schedule is advisable to maintain consistent therapeutic levels.

Interactions of Naltrexone

  1. Opioid Medications: Concurrent use of naltrexone with opioid medications is contraindicated, as it may lead to a diminished analgesic effect and precipitate withdrawal symptoms.
  2. Certain Pain Relievers: Some pain relievers, particularly those with opioid components, may interact adversely with naltrexone.
  3. Liver-Metabolized Drugs: Naltrexone is metabolized in the liver, and interactions with other liver-metabolized drugs may occur, necessitating careful monitoring.

Warnings for Naltrexone

  1. Hepatic Effects: Regular liver function monitoring is advised, especially during the initial stages of treatment.
  2. Opioid Withdrawal: Individuals must be opioid-free for an appropriate duration before initiating naltrexone to prevent precipitated withdrawal.

What Happens During an Overdose?

Though naltrexone overdose is rare, it may lead to liver injury. Immediate medical attention is crucial if an overdose is suspected. Symptoms may include severe nausea, vomiting, and abdominal pain.

What to Avoid When Using Naltrexone

  1. Opioid-Containing Medications: Concurrent use of naltrexone with opioid-containing medications is contraindicated, as it can nullify the therapeutic effects of opioids.
  2. Alcohol Consumption: While naltrexone can reduce alcohol cravings, excessive alcohol consumption is not advised, as it may pose a risk of liver damage.

Alternative Drugs for Naltrexone

  1. Acamprosate: Used in the treatment of alcohol dependence, acamprosate helps maintain abstinence by reducing withdrawal symptoms.
  2. Methadone: An opioid agonist, methadone is utilized in opioid addiction treatment, helping manage withdrawal symptoms and cravings.
  3. Buprenorphine: A partial opioid agonist, buprenorphine aids in opioid addiction treatment by mitigating withdrawal symptoms and cravings.

Also Read: The Immune System: A Working Defense For Your Health


In addiction treatment, naltrexone's ability to mitigate cravings, prevent relapse, and contribute to improved treatment outcomes positions it as a valuable asset in the journey towards recovery. However, its usage requires careful consideration of individual health factors, adherence to dosing guidelines, and ongoing collaboration with healthcare professionals. By navigating the nuanced terrain of naltrexone with awareness and diligence, individuals can forge a path toward sustained sobriety and reclaim control of their lives.


Is Naltrexone Addictive?

No, naltrexone is not addictive. Its mechanism of action involves blocking opioid receptors rather than eliciting addictive effects.

What is Low-Dose Naltrexone (LDN)?

Low-Dose Naltrexone (LDN) explores the use of naltrexone in smaller doses than traditionally prescribed. While research is ongoing, LDN is being investigated for potential applications beyond addiction treatment, including autoimmune conditions and chronic pain.

What Happens if You Drink Alcohol While Taking Naltrexone?

While naltrexone can diminish the desire to drink, moderation is key. Excessive alcohol consumption, especially chronic abuse, can still pose health risks, and individuals should exercise caution.

How Long Does Naltrexone Take to Work?

The onset of naltrexone's effects varies among individuals. While some may experience a reduction in cravings within days, it may take weeks for others. Consistent adherence to the prescribed regimen is crucial for optimal outcomes.

Does Naltrexone Make You Sleepy?

While drowsiness is not a commonly reported side effect of naltrexone, individual responses may vary. If drowsiness occurs, it is advisable to consult with a healthcare professional to explore potential contributing factors.

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