Methylnaltrexone
Relistor (methylnaltrexone) is a prescription medication used to treat opioid-induced constipation in patients with advanced illness who are receiving palliative care. As a peripheral opioid receptor antagonist, it blocks the constipating effects of opioids in the gastrointestinal tract while preserving the pain-relieving effects in the central nervous system.
Relistor treats opioid-induced constipation in patients with advanced illness by blocking opioid receptors in the gut without affecting central nervous system pain relief.
Key facts at a glance
- RxNorm
- 796436
- Generic
- Relistor
- Class
- brand-name
- Brands
- —
- Availability
- rx
- Lactation
- unknown
- Routes
- —
- Forms
- —
- Regions
- US, EU, CN, JP
- Monitoring
- —
This page is for informational purposes only.
Do not use this information to diagnose yourself or to replace a physician's advice. Always consult a qualified healthcare provider before starting, stopping, or changing any medication. If you believe you are experiencing a medical emergency, call your local emergency number immediately.
Relistor is indicated for the treatment of opioid-induced constipation in patients with advanced illness who are receiving palliative care and have not responded adequately to other laxative therapies. It is specifically for patients taking opioid medications for pain management.
Relistor is a peripherally acting mu-opioid receptor antagonist. It selectively blocks opioid receptors in the gastrointestinal tract wall, preventing opioids from slowing bowel movements while maintaining their analgesic effects in the central nervous system.
Relistor is administered by subcutaneous injection. Common side effects include abdominal pain, diarrhea, nausea, and flatulence. It should not be used in patients with known or suspected mechanical gastrointestinal obstruction. Patients should be monitored for symptoms of gastrointestinal perforation. As a brand-name medication, it may be more costly than generic alternatives.
Official drug label
WellAlly may earn a referral fee from linked resources at no extra cost to you. Editorial content is never influenced by commercial relationships.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed July 26, 2026. · Read our editorial policy