naltrexone
Brand names: Vivitrol, ReVia
Naltrexone is a medicine that can help treat alcohol and opioid dependence. It works by blocking the effects of opioids in your body.
Drug Pricing (NADAC)
Brand Price
$1578.75/unit
Generic Price
$0.98/unit
Generic Savings
100%
Generic Available
Yes (5 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Naltrexone is used to treat alcohol dependence and to block the effects of opioid drugs.
Common side effects
Nausea, Headache, Fatigue
Key warnings
Naltrexone can cause serious withdrawal symptoms if you are still using opioids.
How It Works
Naltrexone blocks the effects of opioids by attaching to opioid receptors in the brain. This prevents opioids from having their usual effects, like pain relief or feelings of euphoria. By blocking these effects, naltrexone can help reduce cravings for alcohol or opioids.
How to Take It
If you are dependent on opioids, you must be opioid-free for 7 to 10 days before starting naltrexone. The usual dose for alcoholism is 50 mg once a day. To treat opioid dependence, you may start with 25 mg, then increase to 50 mg a day if you have no withdrawal symptoms. Take naltrexone exactly as prescribed by your doctor.
Pregnancy & Breastfeeding
It is not known if naltrexone is safe to use during pregnancy. Talk to your doctor if you are pregnant or plan to become pregnant. It is also not known if naltrexone passes into breast milk, so talk to your doctor if you are breastfeeding.
Missed Dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule.
Storage
Store naltrexone at room temperature, away from moisture and heat.
Side Effects (from patient reports)
Based on 21,218 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 29,813 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2004–2025.
Total Reports
29,813
Death-Related Reports
1,301
Hospitalization Reports
3,715
Top Indication
Alcoholism
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | INJECTION SITE REACTION | 4,407 |
| 2 | INJECTION SITE PAIN | 3,111 |
| 3 | NAUSEA | 2,094 |
| 4 | ALCOHOLISM | 1,942 |
| 5 | INJECTION SITE MASS | 1,895 |
| 6 | FATIGUE | 1,781 |
| 7 | PAIN | 1,626 |
| 8 | DRUG INEFFECTIVE | 1,498 |
| 9 | HEADACHE | 1,479 |
| 10 | FEELING ABNORMAL | 1,385 |
| 11 | OFF LABEL USE | 1,383 |
| 12 | DRUG DEPENDENCE | 1,369 |
| 13 | MALAISE | 1,239 |
| 14 | INSOMNIA | 1,141 |
| 15 | ANXIETY | 1,083 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
Naltrexone can cause serious withdrawal symptoms if you are still using opioids. Make sure you are opioid-free for at least 7 to 10 days before starting naltrexone. If you experience severe withdrawal symptoms, seek medical help right away.
Known Drug Interactions
Lethargy and somnolence have been reported following doses of naltrexone hydrochloride and thioridazine.
Mechanism: Taking these two drugs together can cause an additive effect that makes you feel very sleepy and tired. Both medications impact the brain in a way that increases drowsiness.
What to do: Tell your doctor if you feel unusually sleepy or sluggish. They may need to monitor your symptoms or adjust your medications.
The safety and efficacy of concomitant use of naltrexone hydrochloride and disulfiram is unknown, and the concomitant use of two potentially hepatotoxic medications is not ordinarily recommended unless the probable benefits outweigh the known risks.
Mechanism: Both of these medications can be hard on the liver. Using them at the same time may increase your risk of developing liver problems.
What to do: This combination is usually avoided unless your doctor decides the benefits are worth the risk. Your doctor should check your liver function regularly.
The pharmacokinetics of acamprosate are not affected by alcohol, diazepam, or disulfiram, and clinically important interactions between naltrexone and acamprosate were not observed [ see Clinical Pharmacology (12.3) ].
Mechanism: These two drugs do not significantly change how the other works in your body.
What to do: You can take these medicines together as no major issues have been found.
There is insufficient information to make a recommendation regarding the concomitant use of naltrexone with MAVYRET.
Mechanism: There is not enough research yet to know exactly how these two drugs affect each other in the body.
What to do: Talk to your doctor before taking these together because the safety of this combination is not yet known.
CONCOMITANT DRUG CLINICAL EFFECT(S) Amphetamines, cocaine, other sympathomimetic agents Additive hypertension, tachycardia, possibly cardiotoxicity Atropine, scopolamine, antihistamines, other anticholinergic agents Additive or super-additive tachycardia, drowsiness Amitriptyline, amoxapine, desipramine, other tricyclic antidepressants Additive tachycardia, hypertension, drowsiness Barbiturates, benzodiazepines, ethanol, lithium, opioids, buspirone, antihistamines, muscle relaxants, other CNS depressants Additive drowsiness and CNS depression Disulfiram A reversible hypomanic reaction was r...
Mechanism: These drugs can have a combined effect that slows down your central nervous system, leading to increased sleepiness.
What to do: Use caution when taking these together and report any excessive drowsiness to your healthcare provider.
Common Questions
Can I take naltrexone if I am taking pain medicine?
How long will I need to take naltrexone?
Will naltrexone cure my addiction?
Can I drink alcohol while taking naltrexone?
What should I do if I experience side effects?
Can I take naltrexone if I am allergic to naloxone?
Will naltrexone show up on a drug test?
Can I stop taking naltrexone suddenly?
Does naltrexone have any effect on my liver?
What is a naloxone challenge test?
What are the common side effects of naltrexone?
Does naltrexone interact with other medications?
What drug class is naltrexone?
Is there a generic version of naltrexone?
Is naltrexone safe during pregnancy?
Related Medications in Opioid Antagonist
Other drugs grouped near naltrexone — same-class peers and common alternatives.
acamprosate
Campral
Acamprosate is a medicine that can help you stay away from alcohol if you are alcohol-dependent and have already stopped drinking.
Compare with naltrexone →
alprazolam
Xanax
Alprazolam (Xanax) is a medication that can help you with anxiety and panic disorders.
Compare with naltrexone →
amitriptyline
Elavil
Amitriptyline is a medicine used to treat depression.
Compare with naltrexone →
amphetamine/dextroamphetamine
Adderall, Adderall XR
Adderall XR is a stimulant medicine.
Compare with naltrexone →
aripiprazole
Abilify
Aripiprazole (Abilify) is a medicine used to treat certain mental disorders and mood problems.
Compare with naltrexone →
Medication Guides
Understanding Drug Interactions
How CYP450 enzymes, inhibitors, and inducers affect your medications
Generic vs Brand Name Drugs
FDA requirements, cost savings, and when the difference matters
Narrow Therapeutic Index Drugs
Why some drugs demand precise dosing and monitoring
Common Drug Interactions
Dangerous medication combinations and how to protect yourself
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What the FDA Data Shows for naltrexone
The FDA label for naltrexone (sold under brand names such as Vivitrol, ReVia) classifies it as a prescription-only medication in the Opioid Antagonist class. Naltrexone is used to treat alcohol dependence and to block the effects of opioid drugs. Official labeling lists 7 commonly reported side effects, including Nausea, Headache, Fatigue.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 21,218 voluntary reports. The database also lists 5 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. NADAC pricing from CMS shows a generic unit cost of $0.98 versus $1578.75 for the brand — a 100% generic savings.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 15, 2023
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages