Recommended Topic Related To:


"Young children have died or become seriously ill from accidental exposure to a skin patch containing fentanyl, a powerful pain reliever. As a result of this, the Food and Drug Administration (FDA) is issuing a Drug Safety Communication to warn pa"...


Relistor Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

Relistor (methylnaltrexone bromide) reduces constipation caused by narcotic medications that are often used to treat pain in people with terminal illness. It is usually given after laxatives have been tried without successful treatment of constipation. Relistor is a special narcotic drug that blocks certain effects of other narcotic medicines. Common side effects include stomach pain, gas, nausea, diarrhea, dizziness, or sweating.

Relistor is administered as a subcutaneous (under the skin) injection. The usual schedule is one dose every other day, but no more than one dose in a 24-hour period Dosage is based on the patient's weight. Relistor may interact with buprenorphine, butorphanol, codeine, hydrocodone, hydromorphone, levorphanol, meperidine, methadone, morphine, nalbuphine, naloxone, oxycodone, oxymorphone or propoxyphene. Tell your doctor all medications you use. Tell your doctor if you are pregnant or plan to become pregnant during treatment with Relistor. It is unknown if this medication passes into breast milk or if it could harm a nursing baby. Consult your doctor before breast-feeding.

Our Relistor (methylnaltrexone bromide) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is Patient Information in Detail?

Easy-to-read and understand detailed drug information and pill images for the patient or caregiver from Cerner Multum.

Relistor in Detail - Patient Information: Side Effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have severe or ongoing diarrhea, stomach pain that will not go away, black or bloody stools, coughing up blood, or nausea or vomiting that are new or worsening symptoms.

Less serious side effects may include:

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

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effect. You may report side effects to FDA at 1-800-FDA-1088.

Read the entire detailed patient monograph for Relistor (Methylnaltrexone Bromide) »

What is Prescribing information?

The FDA package insert formatted in easy-to-find categories for health professionals and clinicians.

Relistor FDA Prescribing Information: Side Effects
(Adverse Reactions)


Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

The safety of RELISTOR was evaluated in two, double-blind, placebo-controlled trials in patients with advanced illness receiving palliative care: Study 1 included a single-dose, double-blind, placebo-controlled period, whereas Study 2 included a 14-day multiple dose, double-blind, placebo-controlled period [see Clinical Studies]. The majority of patients had a primary diagnosis of incurable cancer; other primary diagnoses included end-stage COPD/emphysema, cardiovascular disease/heart failure, Alzheimer's disease/dementia, HIV/AIDS, or other advanced illnesses. Patients were receiving opioid therapy (median daily baseline oral morphine equivalent dose = 172 mg), and had opioid-induced constipation (either < 3 bowel movements in the preceding week or no bowel movement for 2 days). Both the methylnaltrexone bromide and placebo patients were on a stable laxative regimen for at least 3 days prior to study entry and continued on their regimen throughout the study.

The most common ( ≥ 5%) adverse reactions in patients receiving RELISTOR are shown in Table 2 below.

Table 2 : Adverse Reactions from all Doses in Double-Blind, Placebo-Controlled Clinical Studies of RELISTOR in Adult Patients with Opioid-Induced Constipation and Advanced Illness*

Adverse Reaction RELISTOR
N = 165
N = 123
Abdominal Pain 47 (28.5%) 12 (9.8%)
Flatulence 22 (13.3%) 7 (5.7%)
Nausea 19 (11.5%) 6 (4.9%)
Dizziness 12 (7.3%) 3 (2.4%)
Diarrhea 9 (5.5%) 3 (2.4%)
Hyperhidrosis 11 (6.7%) 8 (6.5%)
* Doses: 0.075, 0.15, and 0.30 mg/kg/dose

The rates of discontinuation due to adverse events during the double-blind placebo controlled clinical trials (Study 1 and Study 2) were comparable between RELISTOR (1.2%) and placebo (2.4%).

Postmarketing Experience

The following additional adverse reactions have been identified during post-approval use of RELISTOR. Because they are reported voluntarily from a population of unknown size, estimates of frequency cannot be made. These events have been chosen for inclusion due to either their seriousness, frequency of reporting or causal connection to RELISTOR, or a combination of these factors.


Perforation, cramping, vomiting

General Disorders and Administrative Site

Disorders Diaphoresis, flushing, malaise, pain. Cases of opioid withdrawal have been reported.

Read the entire FDA prescribing information for Relistor (Methylnaltrexone Bromide) »


Report Problems to the Food and Drug Administration


You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Chronic Pain/Back Pain

Find tips and advances in treatment.