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Entereg Side Effects

Generic name: alvimopan

Medically reviewed by Last updated on Apr 23, 2022.

Note: This document contains side effect information about alvimopan. Some of the dosage forms listed on this page may not apply to the brand name Entereg.


More frequent side effects include: constipation. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to alvimopan: oral capsule


Oral route (Capsule)

There was a greater incidence of myocardial infarction in alvimopan-treated patients compared to placebo-treated patients in a 12-month clinical trial, although a causal relationship has not been established. In short-term trials with Alvimopan, no increased risk of myocardial infarction was observed. Because of the potential risk of myocardial infarction with long-term use, alvimopan is available only through a restricted program for short-term use (15 doses) under a Risk Evaluation and Mitigation Strategy (REMS) called the Alvimopan REMS Program.

Side effects requiring immediate medical attention

Along with its needed effects, alvimopan (the active ingredient contained in Entereg) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking alvimopan:

More common

  • Acid or sour stomach
  • belching
  • bloated
  • convulsions
  • decreased urine
  • difficulty having a bowel movement (stool)
  • dry mouth
  • excess air or gas in stomach or intestines
  • full feeling
  • heartburn
  • increased thirst
  • indigestion
  • irregular heartbeat
  • loss of appetite
  • mood changes
  • muscle pain or cramps
  • nausea or vomiting
  • numbness or tingling in hands, feet, or lips
  • pale skin
  • passing gas
  • shortness of breath
  • stomach discomfort, upset, or pain
  • troubled breathing with exertion
  • unusual bleeding or bruising
  • unusual tiredness or weakness

Less common

  • Decrease in frequency of urination
  • decrease in urine volume
  • difficulty in passing urine (dribbling)
  • painful urination

Side effects not requiring immediate medical attention

Some side effects of alvimopan may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

For Healthcare Professionals

Applies to alvimopan: oral capsule


The most commonly reported side effect included dyspepsia.[Ref]


Common (1% to 10%): Dyspepsia[Ref]


1. "Product Information. Entereg (alvimopan)." GlaxoSmithKline (2008):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.