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Pronunciation: METh IL nal TREX own

Brand: Relistor

What is the most important information I should know about methylnaltrexone?

You should not use this medicine if you have a blockage in your stomach or intestines.

What is methylnaltrexone?

Methylnaltrexone is a special narcotic drug that blocks certain effects of other narcotic medicines.

Methylnaltrexone reduces constipation caused by opioid (narcotic) pain medicine used to treat severe chronic pain. Methylnaltrexone works by preventing constipation without reducing the pain-relieving effects of the narcotic.

Methylnaltrexone is used in people with chronic pain that is not caused by cancer, or pain that is caused by advanced terminal illness.

Methylnaltrexone is usually given after laxatives have been tried without successful treatment of constipation.

Methylnaltrexone may also be used for purposes not listed in this medication guide.

What should I discuss with my health care provider before receiving methylnaltrexone?

You should not use methylnaltrexone if you are allergic to it, or if you have:

  • a blockage in your stomach or intestines.

To make sure methylnaltrexone is safe for you, tell your doctor if you have:

  • cancer;
  • a stomach ulcer;
  • history of perforation (a hole or tear) in stomach or intestines; or
  • colitis or other intestinal disorder.

FDA pregnancy category B. Methylnaltrexone is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant during treatment.

It is not known whether methylnaltrexone passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How is methylnaltrexone used?


This medicine is usually given once every other day, but not more often than once every 24 hours.

Methylnaltrexone can produce a bowel movement within 30 minutes after injection.

Prepare your dose in a syringe only when you are ready to give yourself an injection. After loading a syringe, if you cannot give the injection right away keep it at room temperature and use it within 24 hours.



Methylnaltrexone should look clear or slightly yellow in color. Do not use the medication if it has changed colors or has particles in it. Call your doctor for a new prescription.


What happens if I miss a dose?


Do not use this medicine more than once in a 24-hour period.

What happens if I overdose?


What should I avoid while using methylnaltrexone?

Do not use any other laxatives that your doctor has not prescribed.

What are the possible side effects of methylnaltrexone?


Call your doctor at once if you have:

  • extreme dizziness, or feeling like you might pass out;
  • ongoing diarrhea or stomach pain that will not go away;
  • nausea or vomiting that are new or worsening symptoms; or
  • symptoms of narcotic medicine withdrawal --anxiety, sweating, chills, yawning, stomach pain, diarrhea.

Common side effects may include:

  • stomach pain, gas;
  • mild nausea or diarrhea;
  • dizziness, tremors; or
  • increased sweating, hot flashes.


What other drugs will affect methylnaltrexone?


Where can I get more information?

Your doctor or pharmacist can provide more information about methylnaltrexone.



Copyright 1996-2015 Cerner Multum, Inc. Version: 5.02. Revision date: 10/26/2014.
