Naltrexone is an opioid antagonist mainly utilized for treating opioid and alcohol dependence. It functions by inhibiting the pleasurable and calming effects of opioids, thereby helping to diminish cravings and avert relapse. Naltrexone does not lead to physical dependence and possesses no potential for abuse, making it a safer long-term choice for recovery from substance use.

Naltrexone was first approved by the U.S. FDA in 1984 for the treatment of opioid dependence and later in 1994 for alcohol dependence. It is available in oral and injectable forms. Oral tablets (50 mg) are commonly used for daily maintenance therapy, while the extended-release injectable form (given monthly) enhances compliance, especially in patients with difficulty adhering to daily dosing. In India, Naltrexone is widely prescribed under psychiatric and addiction medicine protocols, often as part of a broader rehabilitation plan.

Naltrexone is used for:

• Maintenance treatment in opioid dependence after detoxification
• Reduction of alcohol craving and relapse prevention in alcohol use disorder
• Adjunctive therapy in dual-diagnosis patients (e.g., substance use with mood disorders)
• Investigational use in conditions like compulsive behavior disorders and obesity

 Naltrexone is typically administered as either a daily oral tablet (50 mg) or as a long-acting intramuscular injection (380 mg once a month). Oral dosing is often started after confirming that the patient is opioid-free for 7–10 days to avoid precipitated withdrawal. Patients are advised to take the oral dose at the same time each day to maintain consistent dose levels.

The extended-release injectable formulation is administered by a healthcare professional into the gluteal muscle under sterile conditions. Regular follow-up and monitoring are essential to evaluate compliance and address any side effects.

Common Side Effects:

• Nausea or vomiting
• Headache or dizziness
• Fatigue or sleep disturbances
• Abdominal cramps or loss of appetite
• Joint or muscle pain

Serious Side Effects:

• Liver toxicity (yellowing of skin or eyes, dark urine)
• Severe injection-site reaction (for extended-release form)
• Mood changes, depression, or suicidal thoughts
• Allergic reaction (rash, swelling, difficulty breathing)
• Unexplained bleeding or bruising
   

• Do not use if the patient is currently dependent on opioids or has not completed detox; may precipitate severe withdrawal.
• Avoid in patients with acute hepatitis or liver failure.
• Not recommended for individuals with known hypersensitivity to Naltrexone or any of its components.
• Caution in patients with suicidal ideation or underlying psychiatric illness.
• The injectable form should be administered only by trained professionals to prevent injection-site reactions.

Before starting Naltrexone, make sure you haven’t taken any opioids for at least 7 to 10 days, as it can cause sudden and serious withdrawal symptoms. Your doctor will usually do a urine test to confirm this. Let your doctor know if you have any liver problems, are pregnant, breastfeeding, or planning to become pregnant. Regular blood tests may be needed to check your liver while using this medicine. Avoid taking any opioid-containing medicines, even over-the-counter ones, unless your doctor says it’s okay. If you're having surgery or need pain relief, tell the doctor you’re taking Naltrexone, as it blocks opioid painkillers. Also, carry a medical alert card or wear a bracelet to let emergency doctors know you’re on Naltrexone.

Naltrexone is a support medication, not a cure. Combine it with behavioural therapy, counselling, and a structured recovery program for the best outcomes. Do not try to overcome Naltrexone’s blocking effect by taking large amounts of opioids—it can lead to a life-threatening overdose. Always attend scheduled follow-ups and disclose any changes in mental health to your doctor. If side effects appear serious or persistent, seek medical attention. Keep your healthcare provider informed of all medications you are taking to avoid interactions, especially with liver-metabolised medications.

1. https://www.accessdata.fda.gov/drugsatfda_docs/label/2013/018932s017lbl.pdf
2. https://www.ncbi.nlm.nih.gov/books/NBK534811/
3. https://www.drugs.com/naltrexone.html
4. https://www.ncbi.nlm.nih.gov/books/NBK64042/

The drug information on this page is not a substitute for medical advice; it is meant for educational purposes only. For further details, consult your doctor about your medical condition to know if you are eligible to receive this treatment.