Methylnaltrexone

This information from Lexicomp® explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.

Brand Names: US

Relistor

Brand Names: Canada

Relistor

What is this drug used for?

  • It is used to treat constipation caused by some pain drugs.

What do I need to tell my doctor BEFORE I take this drug?

  • If you are allergic to this drug; any part of this drug; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
  • If you have a bowel block.
  • If you are using another drug like this one. If you are not sure, ask your doctor or pharmacist.
  • If you are breast-feeding. Do not breast-feed while you take this drug.

This is not a list of all drugs or health problems that interact with this drug.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take this drug?

  • Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
  • Be sure to stay close to a bathroom after you use this drug. Most people have a stool within a few minutes to a few hours after using it.
  • Talk with your doctor before using a laxative with this drug.
  • This drug is only for use in patients who take pain drugs. Tell your doctor if you stop taking your pain drug.
  • Signs of opioid withdrawal have happened with this drug. Call your doctor right away if you have sweating, chills, diarrhea or stomach pain that is not normal, anxiety, feeling irritable, or yawning.
  • This drug may not work as well for people who have been taking pain drugs for less than 4 weeks.
  • If you are 65 or older, use this drug with care. You could have more side effects.
  • Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this drug while you are pregnant.
  • If this drug is used during pregnancy, it may cause withdrawal in the unborn baby. A doctor will need to check on the unborn baby after this drug is used.

What are some side effects that I need to call my doctor about right away?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

  • Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
  • Chills.
  • Shakiness.
  • Swelling of belly.
  • Tears in the stomach or bowel wall have happened in certain people taking this drug. Call your doctor right away if you have swelling or pain in your stomach that is very bad, gets worse, or does not go away. Call your doctor right away if you throw up blood or have throw up that looks like coffee grounds; upset stomach or throwing up that does not go away; or black, tarry, or bloody stools.

What are some other side effects of this drug?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

Tablets:

  • Stomach pain or diarrhea.
  • Sweating a lot.
  • Feeling full.
  • Headache.
  • Muscle spasm.
  • Runny nose.
  • Anxiety.

Injection:

  • Stomach pain or diarrhea.
  • Upset stomach or throwing up.
  • Sweating a lot.
  • Gas.
  • Dizziness.
  • Flushing.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to your national health agency.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

How is this drug best taken?

Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.

Tablets:

  • Take on an empty stomach. Take at least 30 minutes before the first meal of the day.
  • Take with a full glass of water.

Injection:

  • It is given as a shot into the fatty part of the skin on the top of the thigh, belly area, or upper arm.
  • If you will be giving yourself the shot, your doctor or nurse will teach you how to give the shot.
  • Wash your hands before and after use.
  • Move the site where you give the shot with each shot.
  • Do not give into red or irritated skin.
  • Do not use if the solution is cloudy, leaking, or has particles.
  • This drug is colorless to a faint yellow. Do not use if the solution changes color.
  • Throw away needles in a needle/sharp disposal box. Do not reuse needles or other items. When the box is full, follow all local rules for getting rid of it. Talk with a doctor or pharmacist if you have any questions.

What do I do if I miss a dose?

  • If you take this drug on a regular basis, take a missed dose as soon as you think about it.
  • If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
  • Do not take 2 doses at the same time or extra doses.
  • Many times this drug is taken on an as needed basis. Do not take more often than told by the doctor.

How do I store and/or throw out this drug?

All products:

  • Store at room temperature in a dry place. Do not store in a bathroom.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.

Tablets:

  • Store in the original container. Do not take out the antimoisture cube or packet.

Injection:

  • Do not freeze.
  • Protect from light.

Vials:

  • If this drug is drawn from a vial into a syringe, it may be stored in the syringe at room temperature for up to 24 hours.
  • Throw away any part of opened vial not used after use.

General drug facts

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else’s drugs.
  • Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • This drug comes with an extra patient fact sheet called a Medication Guide. Read it with care. Read it again each time this drug is refilled. If you have any questions about this drug, please talk with the doctor, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

Consumer Information Use and Disclaimer

This generalized information is a limited summary of diagnosis, treatment, and/or medication information. It is not meant to be comprehensive and should be used as a tool to help the user understand and/or assess potential diagnostic and treatment options. It does NOT include all information about conditions, treatments, medications, side effects, or risks that may apply to a specific patient. It is not intended to be medical advice or a substitute for the medical advice, diagnosis, or treatment of a health care provider based on the health care provider’s examination and assessment of a patient’s specific and unique circumstances. Patients must speak with a health care provider for complete information about their health, medical questions, and treatment options, including any risks or benefits regarding use of medications. This information does not endorse any treatments or medications as safe, effective, or approved for treating a specific patient. UpToDate, Inc. and its affiliates disclaim any warranty or liability relating to this information or the use thereof. The use of this information is governed by the Terms of Use, available at https://www.wolterskluwer.com/en/know/clinical-effectiveness-terms.

Last Reviewed Date

2020-10-26

Copyright

© 2024 UpToDate, Inc. and its affiliates and/or licensors. All rights reserved.

Last Updated

Monday, December 12, 2022