De mest almindelige bivirkninger relateret til lægemidler hos alle de patienter, der har fået methylnaltrexonbromid i alle faser af placebokontrollerede forsøg, var abdominalsmerter, kvalme, diarré og flatulens.
The most common drug-related adverse reactions in all patients exposed to methylnaltrexone bromide during all phases of placebo-controlled studies were abdominal pain, nausea, diarrhoea and flatulence.