Naltrexone: Definition, Mechanism Of Action, Uses, Dosage, Side Effects, Alternativesv

Naltrexone blocks the euphoric and sedative effects of opioids and alcohol, reducing cravings and preventing relapse. According to a study by the National Institute on Drug Abuse (NIDA) titled “Directors Report to the National Advisory Council on Drug Abuse,” 2022, over 1.5 million prescriptions for naltrexone were dispensed for addiction treatment.  

Naltrexone works by competitively binding to mu-opioid receptors, preventing opioid and alcohol-induced dopamine release in the brain’s reward system. This makes alcohol and opioids less pleasurable, reducing cravings and helping individuals maintain sobriety.

Naltrexone is used in medication-assisted treatment (MAT) for opioid and alcohol dependence. It is available in oral tablets (ReVia) and extended-release intramuscular injections (Vivitrol). 

According to a study by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) titled “Treatment of Alcohol Use Disorder,” 2023, naltrexone treatment reduces heavy drinking episodes by 83% when combined with behavioral therapy. 

The side effects of naltrexone range from common issues such as nausea, headache, dizziness, and fatigue to severe effects like liver toxicity, injection site necrosis, and severe allergic reactions. 

According to a study by the National Center for Biotechnology Information (NCBI) titled “Safety Profile and Risks of Naltrexone in Clinical Use,” 2024, 15-20% of patients experience nausea, while injection site reactions occur in up to 20% of extended-release users.

Alternatives to naltrexone for treating opioid and alcohol addiction include buprenorphine, methadone, acamprosate, disulfiram, topiramate, and gabapentin. These medications work by reducing cravings, preventing withdrawal symptoms, or deterring substance use through aversion therapy. 

According to a study by the National Institute on Drug Abuse (NIDA) titled “Medications for Opioid Use Disorder,” 2022, buprenorphine reduces opioid relapse rates by 60-70%, while methadone lowers opioid-related mortality by 50%.

What Is Naltrexone?

Naltrexone is an opioid antagonist that blocks opioid receptors in the brain, preventing the euphoric and sedative effects of opioids and alcohol. It is classified as a non-addictive medication used in medication-assisted treatment for opioid use disorder and alcohol dependence. 

Naltrexone is available under brand names such as Revia (oral tablet) and Vivitrol (extended-release injection). It helps reduce cravings and the risk of relapse. According to a study by the National Institute on Drug Abuse (NIDA) titled “Medications to Treat Opioid Use Disorder,” 2022, naltrexone is effective in preventing relapse, with extended-release formulations improving adherence rates in treatment programs.

What Is The Chemical Composition Of Naltrexone?

The chemical composition of naltrexone is C20H23NO4, with a molecular weight of 341.4 g/mol. Naltrexone is a synthetic opioid antagonist derived from oxymorphone and formulated as naltrexone hydrochloride to enhance solubility for oral and injectable use. The hydrochloride salt form ensures stability and bioavailability in medication-assisted treatment. 

According to a study by the National Center for Biotechnology Information (NCBI) titled “Physicochemical Properties of Naltrexone Hydrochloride,” 2021, the drug has a melting point of 168-170°C and a solubility of 50 mg/mL in water, making it suitable for extended-release formulations used in medication-assisted treatment.

How Is Naltrexone Consumed?

Naltrexone is consumed in oral tablet and intramuscular injection forms, each designed to support adherence in medication-assisted treatment. The oral tablet (ReVia) is taken daily at a standard dose of 50 mg, requiring consistent adherence for effectiveness. The intramuscular injection (Vivitrol) is administered once every four weeks at a dose of 380 mg, ensuring continuous opioid receptor blockade without daily dosing. 

The forms in which naltrexone is consumed are explained below:

• Oral Tablet (ReVia): The oral tablet form is a daily medication taken at 50 mg per dose. It requires consistent adherence to maintain opioid receptor blockade. Daily administration ensures continuous suppression of cravings but poses a challenge for individuals who struggle with routine medication schedules. According to the National Institute on Drug Abuse (NIDA) titled “Medications for Opioid Use Disorder,” 2022, oral naltrexone is effective in preventing relapse but has lower adherence rates compared to extended-release formulations.
• Intramuscular Injection (Vivitrol): The intramuscular injection is a long-acting formulation given once every four weeks at a 380 mg dose. It provides a sustained blockade of opioid receptors, eliminating the need for daily dosing. This improves adherence, particularly for individuals who forget or intentionally skip oral medication. Research from the National Institute on Drug Abuse (NIDA) states that extended-release naltrexone increases treatment retention by 30-40%, making it a preferred option for long-term opioid and alcohol dependence management.

What Is The Mechanism Of Action Of Naltrexone?

The mechanism of action of naltrexone is opioid receptor antagonism, which blocks the effects of opioids and alcohol by competitively binding to mu-opioid receptors. As an opioid receptor antagonist, it prevents opioids from activating reward pathways, eliminating their euphoric and sedative effects. 

In alcohol dependence, naltrexone reduces cravings by modulating neurotransmitters, particularly dopamine, which plays a central role in addiction-related reinforcement. This reduces alcohol’s rewarding effects, helping individuals maintain sobriety. 

The drug has a half-life of 4 hours (oral) and 5-10 days (injectable form) and provides opioid blockade for up to 30 days with extended-release formulations. According to a study by the National Center for Biotechnology Information (NCBI) titled “Naloxone,” 2024, naltrexone has an oral bioavailability ranging from 5-40%, with a half-life of approximately 4 hours for oral administration and 5-10 days for the extended-release injection. 

How Is Naltrexone Used In Addiction Treatment?

Naltrexone is used in addiction treatment like opioid and alcohol use disorder through medication-assisted treatment programs that combine pharmacotherapy with counseling and behavioral interventions. The drug aids in relapse prevention by blocking opioid receptors and reducing the euphoric effects of opioid addiction and alcohol use disorder. 

By diminishing cravings, Naltrexone helps individuals focus on recovery without the constant urge to use substances. In opioid addiction, it is prescribed after detoxification to prevent relapse, while in alcohol use disorder, it decreases alcohol consumption by interfering with the brain’s reward response.

The use of naltrexone in addiction treatments is as follows:

Alcohol Use Disorder

Alcohol use disorder is a chronic condition characterized by compulsive alcohol consumption despite negative consequences. Naltrexone is used in the treatment of alcohol use disorder by reducing cravings and preventing relapse. Naltrexone, as an opioid receptor antagonist, blocks alcohol-induced dopamine release, making drinking less rewarding. This process aids in relapse prevention by lowering the urge to consume alcohol.

The benefits of using naltrexone for alcohol use disorder include a reduction in drinking frequency, improved treatment adherence, and a lower risk of relapse. However, drawbacks include potential liver toxicity in individuals with pre-existing liver conditions and the requirement for strict adherence to maintain effectiveness. 

Research from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) titled “Naltrexone and its effects on craving and alcohol use among patients with alcohol dependence syndromes,” 2024, reports that naltrexone reduces alcohol consumption by 50-60% and decreases relapse rates by 40% in individuals undergoing treatment.

Opioid Use Disorder

Opioid use disorder is a chronic condition characterized by compulsive opioid consumption, leading to physical dependence and withdrawal symptoms. Naltrexone is used in the treatment of opioid use disorder by blocking opioid receptors, preventing opioids from producing euphoric and sedative effects. Naltrexone works as a relapse prevention medication by eliminating the reinforcing effects of opioids, reducing the likelihood of continued use.

The benefits of using naltrexone for opioid use disorder include its non-addictive nature, lack of withdrawal symptoms upon discontinuation, and effectiveness in reducing cravings. However, drawbacks include the need for complete detoxification before initiation and lower adherence rates compared to opioid agonist treatments. 

Research from the National Institute on Drug Abuse (NIDA) titled “The Effectiveness of Medication-Based Treatment for Opioid Use Disorder,” 2019, reports that extended-release naltrexone reduces opioid relapse rates by 65% and lowers cravings in individuals undergoing treatment.

What Is The Recommended Dosage For Naltrexone?

The recommended dosage of naltrexone is 50 mg per day for alcohol dependence and opioid use disorder in its oral tablet form and 380 mg once every four weeks for individuals using intramuscular injection (Vivitrol). 

Dosage adjustments be necessary for individuals with hepatic impairment, requiring lower doses or careful monitoring. Patients must complete opioid detoxification before starting naltrexone for opioid use disorder to avoid withdrawal symptoms.

What Are The Side Effects Of Naltrexone?

The side effects of naltrexone are nausea, headache, dizziness, fatigue, insomnia, vomiting, anxiety, abdominal pain, loss of appetite, and muscle cramps. While most side effects are mild and temporary, serious reactions include liver toxicity, elevated liver enzymes, severe allergic reactions, and injection site reactions in the extended-release intramuscular formulation. 

According to a study by the National Institute on Drug Abuse (NIDA) titled “Directors Report to the National Advisory Council on Drug Abuse,” 2022, 15-20% of patients experience nausea, while 10-15% report headaches and dizziness. Injection site reactions occur in up to 20% of individuals receiving extended-release naltrexone. Liver enzyme elevations are noted in 5-10% of users, requiring regular liver function monitoring.

Common Side Effects Of Naltrexone

The common side effects of naltrexone include nausea, headache, dizziness, fatigue, insomnia, abdominal pain, muscle cramps, and injection site reactions. Most individuals experience mild and temporary side effects that subside as the body adjusts to the medication.

Headaches, nausea, and muscle pain are also frequently reported. The oral tablet form is more likely to cause digestive issues, while the extended-release injection leads to injection site reactions.

The common side effects of naltrexone are:

• Nausea: Nausea is a gastrointestinal reaction that occurs when the stomach lining is irritated. It commonly happens after taking the oral tablet on an empty stomach. Eating small, frequent meals and staying hydrated help minimize this effect.
• Headache: A headache is a temporary discomfort caused by changes in brain chemistry as the body adapts to naltrexone. It often occurs within the first few days of treatment. Drinking plenty of water and getting adequate rest help to alleviate symptoms.
• Dizziness: Dizziness is a balance-related side effect caused by changes in blood circulation and neurotransmitter activity. It is more noticeable when standing up too quickly. Staying hydrated and standing up slowly reduce the risk of dizziness episodes.
• Fatigue: Fatigue is a temporary decrease in energy levels due to the body’s adaptation to naltrexone. It causes sluggishness and difficulty concentrating. Regular physical activity and a balanced diet help combat fatigue.
• Insomnia: Insomnia is a sleep disturbance that results in difficulty falling or staying asleep. It is more common in the first few weeks of treatment. Establishing a bedtime routine and avoiding caffeine in the evening help improve sleep quality.
• Abdominal Pain: Abdominal pain is a digestive discomfort that results from mild gastrointestinal irritation. It is accompanied by bloating or indigestion. Taking naltrexone with food reduces stomach irritation and discomfort.
• Muscle Cramps: Muscle cramps are involuntary muscle contractions that cause stiffness and discomfort. They usually occur in the legs or back. Staying hydrated, stretching regularly, and increasing magnesium intake help alleviate muscle cramping.
• Injection Site Reactions: Injection site reactions are localized skin irritations caused by the extended-release intramuscular injection. Symptoms include pain, swelling, redness, and irritation at the injection site. Applying a cold compress reduces inflammation and discomfort.

Severe Side Effects Of Naltrexone

Severe side effects of naltrexone include liver toxicity, severe allergic reactions, injection site necrosis, depression, suicidal thoughts, increased blood pressure, hallucinations, and respiratory issues. These effects are rare but require immediate medical attention if they occur.

According to a study by the National Center for Biotechnology Information (NCBI) titled “Safety Profile and Risks of Naltrexone in Clinical Use,” 2024, liver enzyme elevations occur in 5-10% of patients, while injection site necrosis affects 1-2% of extended-release users. Depression and suicidal thoughts are observed in 3-5% of individuals undergoing treatment.

Severe side effects of naltrexone are:

• Liver Toxicity: Liver toxicity is a serious risk associated with naltrexone use, particularly in individuals with pre-existing liver conditions. It leads to elevated liver enzymes and hepatitis, requiring regular liver function tests to monitor potential damage. Symptoms include jaundice, dark urine, and upper abdominal pain.
• Severe Allergic Reactions: Severe allergic reactions are immune system responses triggered by naltrexone. Symptoms include rash, swelling of the face or throat, difficulty breathing, and itching. Immediate medical intervention is necessary to prevent life-threatening complications.
• Injection Site Necrosis: Injection site necrosis is a rare but serious reaction to the extended-release intramuscular injection. It causes severe tissue damage, leading to pain, ulceration, and possible surgical intervention. Proper injection techniques and monitoring help prevent this condition.
• Depression: Depression is a mental health side effect that develops during treatment. Some individuals experience persistent sadness, loss of interest, and emotional distress. Patients with a history of mental illness should be closely monitored while using naltrexone.
• Suicidal Thoughts: Suicidal thoughts are a serious psychological side effect linked to naltrexone. Individuals develop self-harm ideation or increased emotional instability. Any signs of suicidal behavior require immediate medical evaluation and intervention.
• Increased Blood Pressure: Increased blood pressure is a cardiovascular risk in some patients taking naltrexone. It causes headaches, dizziness, or a rapid heartbeat. Regular blood pressure monitoring is advised, especially for those with hypertension.
• Hallucinations: Hallucinations are neurological side effects that occur in rare cases. Individuals experience visual or auditory distortions, confusion, or paranoia. This requires immediate discontinuation and medical evaluation.
• Respiratory Issues: Respiratory issues involve shortness of breath, wheezing, or difficulty breathing, particularly in individuals with underlying lung conditions. Immediate medical attention is necessary if breathing problems develop.

Does Naltrexone Make You Sleepy?

No, naltrexone does not cause sleepiness, but drowsiness and fatigue are reported in some individuals. While it does not have sedative properties, some users experience mild fatigue as their body adjusts to the medication. 

According to a study by the National Institute on Drug Abuse (NIDA) titled “DESPR Research Highlights,” 2017, drowsiness occurs in a small percentage of patients, often during the early stages of treatment. However, this effect is temporary and usually subsides within a few days.

What Are The Alternatives To Naltrexone?

Alternatives to naltrexone are Buprenorphine, Methadone, Acamprosate, Disulfiram (Antabuse), Topiramate, and Gabapentin. Each has unique mechanisms of action and benefits. These medications help manage cravings, withdrawal symptoms, and relapse prevention, improving long-term recovery outcomes. The choice of medication depends on individual needs, medical history, and treatment goals.

The alternatives to naltrexone are:

• Buprenorphine: Buprenorphine is a partial opioid agonist that activates opioid receptors at a lower intensity than full opioids, reducing withdrawal symptoms and cravings without producing strong euphoria. It is frequently prescribed in medication-assisted treatment (MAT), either alone or combined with naloxone (as Suboxone) to deter misuse. According to a study by the National Institute on Drug Abuse (NIDA) titled “Medications for Opioid Use Disorder,” 2022, buprenorphine reduces opioid relapse rates by 60-70% and improves treatment retention.
• Methadone: Methadone is a full opioid agonist that binds to opioid receptors, preventing withdrawal symptoms and reducing cravings while allowing individuals to function normally. Unlike naltrexone, which blocks opioid effects, methadone provides controlled activation, supporting long-term maintenance therapy. According to the National Institute on Drug Abuse (NIDA), methadone reduces opioid-related mortality by 50% and lowers illicit opioid use.
• Acamprosate: Acamprosate is a glutamate modulator that stabilizes brain activity altered by chronic alcohol consumption. It does not treat withdrawal symptoms but reduces alcohol cravings and relapse risk by restoring normal neurotransmitter balance. Research from the National Institute on Alcohol Abuse and Alcoholism (NIAAA) titled “Treatment of Alcohol Use Disorder,” 2023, found that acamprosate increases abstinence rates by 30-50% in individuals undergoing treatment for alcohol dependence.
• Disulfiram (Antabuse): Disulfiram is an alcohol-deterrent medication that causes severe nausea, flushing, and palpitations when alcohol is consumed. Unlike naltrexone, which reduces cravings, disulfiram acts as a behavioral deterrent, creating an aversion to alcohol. According to the National Center for Biotechnology Information (NCBI) titled “Pharmacological Interventions for Alcohol Use Disorder,” 2011, disulfiram reduces drinking frequency by 40-50% when used in supervised treatment programs.
• Topiramate: Topiramate is an anti-epileptic medication that influences GABA and glutamate neurotransmission, reducing alcohol cravings and binge drinking episodes. Unlike naltrexone, it does not block alcohol’s effects but regulates impulsive drinking behavior. According to a study by NCBI titled “Neuroscientific Basis of Treatment for Substance Use Disorders,” 2022, topiramate reduces heavy drinking episodes by 20-30%. It is recommended as a second-line treatment for alcohol use disorder. 
• Gabapentin: Gabapentin is a neuromodulatory medication used to reduce alcohol withdrawal symptoms and relapse risk by stabilizing neurotransmitter activity. It is commonly prescribed alongside other treatments for enhanced long-term sobriety outcomes. A study by NCBI titled “Alcohol Use Disorder and Pharmacological Treatments,” 2016, found that gabapentin reduces alcohol cravings by 30-40% and helps manage withdrawal-related anxiety.

Can You Take You Take Disulfiram And Naltrexone Together?

Yes, you can take disulfiram and naltrexone together, but this combination should be used with caution and under medical supervision. Disulfiram works by causing severe reactions to alcohol consumption, while naltrexone reduces alcohol cravings and blocks its euphoric effects. 

When combined, they improve treatment adherence for individuals with alcohol use disorder, but the risk of side effects, including liver toxicity and increased depressive symptoms, is higher. 

According to a study by the National Center for Biotechnology Information (NCBI) titled “Pharmacological and Physical Interventions for Alcohol-Use Disorders,” 2011, individuals using both medications had higher abstinence rates compared to those using either drug alone but experienced more adverse effects, particularly nausea and fatigue.

Can You Take You Take Acamprosate And Naltrexone Together?

Yes, you can take acamprosate and naltrexone together, as they target different aspects of alcohol use disorder and enhance treatment effectiveness. Naltrexone blocks opioid receptors to reduce alcohol’s euphoric effects, while acamprosate modulates glutamate neurotransmission, stabilizing brain chemistry altered by chronic alcohol use. 

According to a study by the National Institute on Alcohol Abuse and Alcoholism (NIAAA) titled “Treatment of Alcohol Use Disorder,” 2023, combining acamprosate and naltrexone leads to higher abstinence rates compared to using either medication alone, with an increase in alcohol-free days by up to 30%.

How Does Naltrexone Work For Alcohol Addiction Treatment?

Naltrexone works for alcohol addiction treatment by blocking opioid receptors, reducing alcohol’s rewarding effects, and decreasing cravings. It prevents the release of dopamine triggered by alcohol consumption, making drinking less pleasurable. 

This process helps individuals undergoing alcohol addiction treatment control alcohol intake and supports relapse prevention. Unlike medications that cause adverse reactions to alcohol, naltrexone allows individuals to drink but reduces the motivation to continue. It is most effective when combined with counseling and behavioral therapy in medication-assisted treatment programs.

Who Should Avoid Taking Naltrexone?

Those who should avoid taking naltrexone have conditions like current opioid use, liver disease, pregnancy and breastfeeding, severe kidney disease, active alcohol use in an extended-release form, severe depression, or suicidal thoughts. Since naltrexone is not suitable for everyone, certain individuals should avoid its use due to potential health risks and adverse reactions. 

Those who should avoid taking naltrexone have the following conditions:

• Current Opioid Use: Naltrexone is a pure opioid antagonist that blocks opioid receptors, leading to immediate withdrawal symptoms if taken while opioids are still in the system. It should only be started after a 7-10 day opioid-free period to prevent precipitated withdrawal. According to the Food and Drug Administration (FDA) guidelines in the study titled “Medications for Opioid Use Disorder,” 2023, patients taking opioids must undergo detoxification before starting naltrexone to avoid severe withdrawal reactions. 
• Liver Disease: Naltrexone is metabolized in the liver, increasing the risk of hepatic toxicity in individuals with liver impairment, hepatitis, or cirrhosis. It causes elevated liver enzymes, leading to further complications. Liver function tests are necessary before and during treatment to assess safety. A study by the National Center for Biotechnology Information (NCBI) titled “Naltrexone Safety and Hepatic Function,” 2024, states that 5-10% of patients experience liver enzyme elevations, requiring monitoring.
• Pregnancy and Breastfeeding: Naltrexone is classified as an FDA Pregnancy Category C drug, meaning there is insufficient human data to confirm safety during pregnancy. Animal studies suggest potential fetal risks, and they pass into breast milk. Pregnant women should only take naltrexone if the benefits outweigh the risks, under strict medical supervision.
• Severe Kidney Disease: Since naltrexone and its metabolites are excreted through the kidneys, individuals with renal impairment experience delayed drug clearance, increasing the risk of drug accumulation and toxicity. Dose adjustments are necessary for those with mild to moderate kidney dysfunction.
• Active Alcohol Use in Extended-Release Form: The extended-release intramuscular injection (Vivitrol) should be used cautiously in individuals who continue to drink alcohol, as it increases the risk of liver toxicity and psychiatric side effects.
• Severe Depression or Suicidal Thoughts: Naltrexone has been associated with increased depressive symptoms in some individuals. Those with a history of severe depression or suicidal ideation should be closely monitored for mood changes during treatment.

Can You Use Naltrexone While Still Taking Opioids?

No, you cannot use naltrexone while still taking opioids. Naltrexone is a pure opioid antagonist that immediately binds to opioid receptors, displacing any existing opioids and triggering precipitated withdrawal. This sudden withdrawal causes severe nausea, vomiting, muscle pain, sweating, and agitation. To prevent this, opioid detoxification is required before starting naltrexone, ensuring the body is free of opioids for at least 7-10 days.

Can You Drink Alcohol While On Naltrexone?

Yes, you can drink alcohol while on naltrexone because it does not cause sickness like disulfiram. Instead, it works by blocking opioid receptors, reducing the pleasurable effects of alcohol, and helping with craving control. This makes drinking less rewarding, discouraging further alcohol consumption. While it does not prevent intoxication, individuals taking naltrexone often experience a decreased urge to continue drinking alcohol, supporting relapse prevention in alcohol use disorder treatment.

Is Naltrexone A Controlled Substance?

No, naltrexone is not a controlled substance because it does not produce euphoria, physical dependence, or addiction. As an opioid receptor antagonist, it blocks the effects of opioids and alcohol without activating reward pathways in the brain. Unlike methadone or buprenorphine, which have some opioid activity, naltrexone has no misuse potential and is prescribed without the same level of regulatory restrictions. 

According to the National Institute on Drug Abuse (NIDA) titled “Directors Report to the National Advisory Council on Drug Abuse,” 2022, naltrexone has no abuse liability. It is not subject to Controlled Substances Act regulations.

Do You Need A Prescription For Naltrexone?

Yes, you need a doctor’s prescription for naltrexone in the U.S. because it is a prescription-only medication regulated by healthcare authorities. It must be obtained through a licensed healthcare provider who assesses the patient’s medical history and ensures opioid detoxification before initiating treatment. 

Both oral tablets (ReVia) and extended-release injections (Vivitrol) require a prescription, and a medical professional administers the injectable form.

Can You Overdose On Naltrexone?

No, you cannot overdose on naltrexone in the same way as opioids or other depressants because it does not cause respiratory depression or sedation. However, taking excessive doses leads to liver toxicity, nausea, vomiting, and dizziness. The primary risk associated with naltrexone is its opioid-blocking effect, which leads individuals to take higher opioid doses to overcome the blockade, increasing the risk of fatal opioid overdose. 

According to a study by the National Institute on Drug Abuse (NIDA) titled “DESPR Research Highlights,” 2017, individuals who discontinue naltrexone and relapse into opioid use face a higher risk of overdose due to reduced opioid tolerance. 

Is Naltrexone Addictive?

No, naltrexone is not addictive because it does not activate opioid receptors or produce euphoria, dependence, or withdrawal symptoms upon discontinuation. As an opioid antagonist, it blocks opioid effects rather than stimulating them, eliminating the potential for misuse. Unlike opioid-based treatments such as methadone or buprenorphine, naltrexone has no reinforcing properties, making it a safer option for long-term recovery. 

According to a study by the National Center for Biotechnology Information (NCBI) titled “Naltrexone and its effects on craving and alcohol use among patients with alcohol dependence syndromes,” 2024, there is no evidence of physical or psychological dependence associated with naltrexone use.

Can You Stop Taking Naltrexone Suddenly?

Yes, you can stop taking naltrexone suddenly because it does not cause withdrawal or physical dependence. However, discontinuing it increases relapse risk, as opioid and alcohol cravings return without receptor blockade. To ensure a smooth transition, medical guidance is recommended, especially for individuals in medication-assisted treatment programs.

Does Naltrexone Have Withdrawal Symptoms?

No, naltrexone does not cause withdrawal symptoms because it does not activate opioid receptors or lead to dependence. However, if taken while opioids are still in the system, it triggers precipitated withdrawal, a rapid and intense onset of withdrawal symptoms. To avoid this, individuals must complete opioid detoxification before starting naltrexone.

How Long Does Naltrexone Stay In Your System?

Naltrexone stays in your system for 4-6 hours after an oral dose and 5-10 days after an extended-release injection due to its longer half-life. It is detected in urine for up to 24 hours, blood for 24-48 hours, saliva for up to 12 hours, and hair for up to 90 days. Detection varies based on dosage, metabolism, and test sensitivity.

According to a study by the National Center for Biotechnology Information (NCBI) titled “Pharmacokinetics of Naltrexone in Clinical Use,” 2024, the extended-release injection shows detectable plasma levels for up to 30 days, supporting its use in long-term addiction treatment.