Naltrexone
Also known as: ReVia, Naltima, Nodict
Important: This is informational content only. Always consult Dr. Ambrish Singal or your psychiatrist before starting, stopping, or changing any medication.
What is Naltrexone?
Naltrexone is an opioid receptor antagonist used for alcohol dependence and opioid addiction prevention. It blocks the rewarding effects of alcohol and opioids, reducing cravings and relapse risk.
How It Works
Competitively blocks mu-opioid receptors, preventing the euphoric effects of opioids. For alcohol, it modulates the endogenous opioid system involved in alcohol reward, reducing the pleasurable effects of drinking.
Uses
How This Drug Starts Working
Effects typically begin within 1-4 weeks depending on the condition being treated. Full therapeutic effect usually takes 4-8 weeks.
Week-by-Week Timeline
Week 1: Medication reaching therapeutic blood levels. Some initial side effects may appear as body adjusts.
Week 2-3: Initial therapeutic effects beginning. Side effects often settling.
Week 4-6: Significant therapeutic benefit in most patients.
Week 8+: Full effect established. Treatment response can be properly assessed.
What Changes First?
Physical symptoms (sleep, appetite, energy) typically improve before emotional and cognitive symptoms. Others may notice improvement before you feel it yourself.
Why Does It Take Time?
Psychiatric medications work by gradually rebalancing brain chemistry and neural circuits. Unlike pain medications that block a sensation, these drugs help your brain rebuild healthy patterns — which requires time.
Complete Dosage Guide
How to Take
Take exactly as prescribed by your doctor. Maintain consistent timing each day.
Starting Dose
Your doctor will determine the appropriate starting dose based on your condition, age, weight, and other factors.
Dose Increases
Dose adjustments are made gradually based on your response and side effects. Follow your doctor's instructions for any changes.
Maximum Dose
Your doctor will not exceed safe maximum doses. Never take more than prescribed.
When to Take
Take at the same time daily for best results. Ask your doctor whether morning or evening is better for your specific medication.
If You Miss a Dose
If you miss a dose, take it as soon as you remember unless close to your next dose. Never double up. Contact your doctor if you miss multiple doses.
Food & Drink
Ask your doctor or pharmacist about specific food interactions for your medication.
How Long to Take
Duration of treatment varies by condition. Never stop medication without discussing with your doctor first — some medications require gradual tapering.
Dosage by Age Group
adult
Oral: 50mg once daily. Extended-release injection (Vivitrol): 380mg IM monthly. For opioid dependence: Start ONLY after 7-10 days opioid-free.
child
Not recommended for children.
elderly
Same as adult dosing. Monitor liver function.
Special Populations
Pregnancy
Category C. Limited data. Use only if benefit outweighs risk.
Kidney Conditions
No dose adjustment in mild-moderate impairment.
Liver Conditions
AVOID in acute hepatitis or liver failure. Monitor liver function regularly.
Side Effects
Common
- Nausea
- Headache
- Dizziness
- Fatigue
- Anxiety
- Joint/muscle pain
- Insomnia
Serious
- Hepatotoxicity (dose-related)
- Precipitated opioid withdrawal (if opioids in system)
- Depression
- Injection site reactions (IM form)
What You Should Know
Overdose Risks
Naltrexone overdose is generally not life-threatening. May cause nausea, abdominal pain, and liver damage at very high doses.
Safe Discontinuation
Can be stopped without tapering. No withdrawal syndrome from naltrexone itself. However, patients may be at risk of opioid overdose if they resume use after stopping (lowered tolerance).