Applies to methylnaltrexone: oral tablet. Other dosage forms:

• subcutaneous solution

Serious side effects of Methylnaltrexone

Along with its needed effects, methylnaltrexone 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 methylnaltrexone:

Incidence not known

• Chills
• diarrhea
• fear or nervousness
• increased sweating
• severe abdominal or stomach pain
• severe or persistent diarrhea
• yawning

Other side effects of Methylnaltrexone

Some side effects of methylnaltrexone 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

• Full or bloated feeling
• headache
• muscle spasms
• pressure in the stomach
• runny nose
• swelling of the abdominal or stomach area
• vomiting

For Healthcare Professionals

Applies to methylnaltrexone: oral tablet, subcutaneous kit, subcutaneous solution.

Gastrointestinal

Very common (10% or more): Abdominal pain (up to 29%), flatulence (up to 13%), nausea (up to 12%)

Common (1% to 10%): Diarrhea,

Postmarketing reports: Perforation, cramping, vomiting^[Ref]

Nervous system

Common (1% to 10%): Dizziness, tremor^[Ref]

Dermatologic

Common (1% to 10%): Hyperhidrosis, flushing^[Ref]

Other

Common (1% to 10%): Chills

Postmarketing reports: Malaise, pain, cases of opioid withdrawal^[Ref]

Cardiovascular

In an open-label, uncontrolled study (n=1034), 4 myocardial infarctions (1 fatal), 1 stroke (fatal), 1 fatal cardiac arrest, and 1 sudden death were reported. It is not possible to establish a relationship between these events and use of this drug.^[Ref]

Frequency not reported: Myocardial infarctions^[Ref]

General

The most common adverse reactions included abdominal pain, nausea, diarrhea, hyperhidrosis, hot flush, tremor, and chills.^[Ref]

Local

Common (1% to 10%): Injection site reactions including stinging, burning, pain, redness, and edema^[Ref]