Common use of Naltrexone
Naltrexone is a non-addictive opioid receptor antagonist most commonly used to treat alcohol use disorder (AUD) and opioid use disorder (OUD). By blocking mu-opioid receptors, it reduces cravings and prevents the euphoric and reinforcing effects of alcohol and opioids. For alcohol use disorder, it helps people drink less or maintain abstinence; for opioid use disorder, it supports relapse prevention after detoxification. It is not a treatment for acute opioid overdose—that role belongs to naloxone—and it does not manage acute alcohol withdrawal symptoms. Naltrexone works best when combined with counseling, peer support, and structured recovery programs.
Two prescription forms exist: oral tablets taken daily and an extended-release intramuscular injection administered once every 4 weeks. Off-label, low-dose naltrexone (LDN) in much smaller nightly doses is explored for conditions such as fibromyalgia, neuropathic pain, and certain autoimmune disorders; evidence is evolving and it is not FDA-approved for these indications. People who may need opioid pain medicines (for planned surgery or severe injuries) should discuss timing and alternatives before starting naltrexone, because it can block pain-relieving opioids for days after a dose.
Dosage and direction
For alcohol use disorder, a common oral dose is 50 mg once daily. Some clinicians start with 25 mg on day one to assess tolerability before moving to 50 mg. Alternative schedules (for example, 100 mg on some days) may be used to improve adherence under medical supervision. For opioid use disorder, oral naltrexone 50 mg daily is an option, but many patients prefer the extended-release injection (380 mg intramuscularly every 4 weeks) to avoid daily dosing and reduce the risk of missed tablets. The injectable form must be administered by a healthcare professional.
Before starting naltrexone for OUD, you must be opioid-free to avoid precipitated withdrawal. Typically, that means at least 7–10 days after short-acting opioids (like oxycodone or heroin) and 10–14 days or longer after long-acting opioids or buprenorphine/methadone, guided by your clinician. A naloxone challenge or a negative urine opioid screen may be used to confirm readiness. For AUD, an opioid-free period is not required, but people taking any opioid-containing medications should stop and clear them first. Off-label low-dose naltrexone is often titrated from 0.5–1 mg nightly, increasing gradually to 3–4.5 mg as tolerated; dosing and use should be individualized with a knowledgeable prescriber.
Take oral tablets at the same time each day, with or without food. If nausea occurs, taking with food or in the evening can help. Do not crush or chew unless your pharmacist advises that it is safe for your specific product. Continue behavioral therapies and follow-up appointments—medication works best as part of a comprehensive plan.
Precautions
Liver health is central to safe use. Naltrexone can elevate liver enzymes, especially at higher-than-recommended doses. Most clinicians obtain baseline liver function tests and monitor periodically, particularly if you have chronic hepatitis, fatty liver disease, or heavy alcohol use. Seek medical attention promptly if you develop signs of liver injury such as unusual fatigue, dark urine, right upper abdominal pain, or yellowing of the skin or eyes.
Tell your clinician about all medical conditions. Use caution if you have renal impairment, a history of depression or suicidal thoughts, or are pregnant or breastfeeding; shared decision-making is essential. Because naltrexone blocks opioids, you may not respond to standard opioid pain medicines. Wear a medical ID or carry a wallet card indicating that you take an opioid antagonist, so emergency teams can plan appropriate pain control. During the first days, some people experience dizziness or drowsiness; avoid driving or hazardous tasks until you know how you respond.
Contraindications
Do not use naltrexone if you are currently taking opioid medications, have physiologic opioid dependence, are in acute opioid withdrawal, or have a positive opioid screen. It is contraindicated in acute hepatitis or liver failure and in anyone with a known hypersensitivity to naltrexone or its components. Naltrexone should not be initiated in people on methadone or buprenorphine maintenance. If you are likely to need opioid analgesia imminently (for example, major planned surgery without a non-opioid plan), discuss timing as initiation may need to be deferred.
Possible side effects
Most people tolerate naltrexone well. Common side effects include nausea, stomach cramps, decreased appetite, headache, dizziness, fatigue, insomnia, anxiety, irritability, and joint or muscle aches. These often improve over 1–2 weeks. Taking tablets with food or shifting the dosing time can reduce nausea or sleep issues. Some people report vivid dreams, particularly with low-dose naltrexone; lowering the dose or taking it earlier in the evening may help.
Less common effects include increased liver enzymes and, rarely, clinically significant hepatitis—symptoms include persistent nausea, abdominal pain, dark urine, or jaundice. The extended-release injection can cause injection-site pain, swelling, induration, or nodules; rare but serious reactions such as tissue necrosis or abscess have been reported and require medical attention. Because naltrexone blocks opioids, taking it too soon after opioid use can precipitate sudden, severe withdrawal; this is preventable with proper timing and screening. Allergic reactions are uncommon but possible; seek urgent care if you experience hives, swelling, wheezing, or difficulty breathing. Discuss risks and benefits with your clinician, particularly if you have coexisting medical conditions.
Drug interactions
The most important interaction is with opioid-containing products. Naltrexone blocks prescription opioids (e.g., codeine, hydrocodone, oxycodone, morphine, fentanyl), some cough syrups containing codeine, and certain anti-diarrheals derived from opioids. Using opioids while on naltrexone can lead to inadequate pain control, and attempting to “override” the blockade with high opioid doses is dangerous and can cause overdose, especially as naltrexone wears off. Plan ahead for procedures or surgeries; non-opioid and regional anesthesia strategies may be needed, and stopping naltrexone for an appropriate interval may be advised by your prescriber.
Naltrexone is not a significant CYP450 inhibitor or inducer, so it has few metabolic drug–drug interactions. However, additive liver risk should be considered with other hepatotoxic agents, including high-dose acetaminophen, isoniazid, valproate, or disulfiram. Alcohol use itself can stress the liver. Dextromethorphan (a common cough suppressant) is not an opioid agonist and is not blocked by naltrexone, but combination products may also contain codeine—check labels carefully. Always provide your full medication and supplement list to your pharmacist to screen for interactions and to ensure safe perioperative plans.
Missed dose
If you miss an oral dose, take it when you remember unless it is close to the time for your next dose—if so, skip the missed dose and resume your regular schedule. Do not double up. If you miss an extended-release injection appointment, contact your provider promptly to reschedule; staying on schedule helps maintain the therapeutic blockade. For low-dose naltrexone, follow your prescriber’s instructions; most can simply resume the usual dose the next day if only one dose was missed.
Overdose
Naltrexone overdose is uncommon but can increase the risk of liver injury and worsen side effects such as nausea, vomiting, dizziness, or abdominal pain. If you or someone else may have taken more than prescribed, call your clinician or U.S. Poison Control at 1-800-222-1222 right away, or seek emergency care—especially if severe symptoms, confusion, fainting, or yellowing of the skin or eyes occur. Bring the medication bottle or packaging and a list of all medicines and supplements to assist healthcare professionals in providing appropriate care.
Storage
Store oral naltrexone tablets at room temperature (generally 20–25°C/68–77°F), away from excess heat, moisture, and light. Keep the bottle tightly closed and out of reach of children and pets. The extended-release injection supplied by healthcare providers is typically refrigerated per manufacturer instructions; do not freeze. Follow the package insert and clinic protocol for handling and preparation. Never use expired medication, and dispose of unused doses safely according to pharmacy guidance.
U.S. sale and prescription policy
In the United States, naltrexone is a prescription medication. HealthSouth Hospital of Altamonte Springs provides a legal and structured pathway to access naltrexone without a prior in‑hand prescription by coordinating an integrated, compliant telehealth process. After you complete a secure online intake, a licensed clinician reviews your medical history, screens for contraindications (including recent opioid use and liver conditions), and, if appropriate, issues a prescription that our pharmacy dispenses. This ensures you are not shipped naltrexone without prescriber authorization while sparing you the need for a separate clinic visit.
Services are available to eligible adults in permitted states, with identity verification, age requirements, and safeguards aligned with federal and state regulations. Not all requests will be approved; clinical judgment and safety guide every decision. We offer discreet delivery, medication counseling, and coordination with your broader care team upon request. This service is not for emergencies. If you require urgent medical attention or are experiencing severe withdrawal or overdose, call 911. For coverage questions, costs, and state availability, contact HealthSouth Hospital of Altamonte Springs’s customer care team.
