Last reviewed 2026-04-20 · How we verify

Naltrexon

At a glance

Approved indications

• Alcoholism
• Chronic Pain with Opioid Tolerance
• Chronic pain
• Obesity
• Prevention of opioid abuse
• Severe Pain with Opioid Tolerance
• Severe pain
• Therapeutic opioid induced constipation

Common side effects

• Nausea
• Headache
• Dizziness
• Nervousness
• Fatigue
• Insomnia
• Vomiting
• Anxiety
• Somnolence
• Abdominal cramps
• Restlessness
• Bone or joint pain

Serious adverse events

• Hepatocellular injury
• Precipitated opioid withdrawal
• Depression
• Suicidal ideation
• Suicidal attempts

Key clinical trials

• Pharmacological and Behavioral Treatment After Bariatric Surgery: Acute (Stage 1) (PHASE2, PHASE3)
• Lemborexant Augmentation of Naltrexone for Alcohol Craving and Sleep (PHASE3)
• Preoperative Weight Loss for Open Abdominal Wall Reconstruction (NA)
• A Multiple Health Behavior Change (MHBC) Intervention for Weight Loss and Smoking Cessation for Pre-Bariatric Surgery Patients (PHASE1, PHASE2)
• Low-dose Naltrexone for Post-COVID Fatigue Syndrome (PHASE2)
• Development of a MHBC Intervention for Weight Loss and Smoking Cessation for Pre-Bariatric Surgery Patients (PHASE1)
• Combination Gerotherapeutic Interventions for Healthspan Improvement (PHASE3)
• Individualized Pharmacological Approach to Obesity in Patients With Bipolar Disorder (PHASE4)

Patents

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

Competitive intelligence

For the full competitive landscape — auto-detected comparators, recent regulatory actions across the set, upcoming PDUFA, patent timeline, sponsor landscape:

• Naltrexon CI brief — competitive landscape report
• Naltrexon updates RSS · CI watch RSS
• Institute of Liver and Biliary Sciences, India portfolio CI