Stomach/abdominal pain may occur. If this effect lasts or gets worse, tell your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Stop taking naldemedine and tell your doctor right away if you have diarrhea that doesn't stop.
Opioid withdrawal symptoms may occur in some people. Tell your doctor right away if any of these withdrawal symptoms occur: sweating, chills, abdominal cramps, diarrhea, mental/mood changes (such as anxiety, confusion, extreme sleepiness, visual hallucinations), unusual yawning.
This drug may rarely cause a serious tear in the stomach or intestinal wall (perforation). Stop taking this medication and get medical help right away if any of these very serious side effects occur: severe stomach/abdominal pain that doesn't go away, fever, severe dizziness, fainting, severe nausea/vomiting.
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.