Methylnaltrexone

Name: Methylnaltrexone Drug Interactions
Creator: Dr. Brian Staiger, PharmD, BCPS

5 interactions 29 cited references

Also sold as: Relistor Relistor®

About Methylnaltrexone

Methylnaltrexone is used to treat constipation caused by opioid (narcotic) pain medications in people with chronic (ongoing) pain that is not caused by cancer but may be related to a previous cancer or cancer treatment. Methylnaltrexone is in a class of medications called peripherally acting mu-opioid receptor antagoni… Read the full Methylnaltrexone drug information page →

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated Aug 9, 2026 · Editorial policy · Data sources

Sources: FDA prescribing information (Structured Product Labeling), the published literature cited in each entry, DDInter 2.0 (a major open-access drug-interaction database), and legacy DrugBank interaction data distributed by the NIH's RxNav service (decommissioned in 2024) — analyzed and reviewed by our pharmacist team. How we build this library →

Most serious with: Morphine Morphine Sulfate Liposome Naldemedine Naloxegol Morphine Injection

5 Major

All (5) Major (5)

Major

Methylnaltrexone Morphine Decreased opioid efficacy and precipitation of opioid withdrawal Details Methylnaltrexone Morphine Sulfate Liposome Decreased opioid efficacy and precipitation of opioid withdrawal Details Methylnaltrexone Naldemedine Symproic Increased risk of opioid withdrawal Details Methylnaltrexone Naloxegol Movantik Risk of opioid withdrawal Details Methylnaltrexone Morphine Injection Astramorph® PF Decreased opioid efficacy and precipitation of opioid withdrawal Details

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Educational information only, not medical advice. Always confirm interactions with your pharmacist or prescriber before making any change to your medications.