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Drug

Methylnaltrexone

Pronounced

"METH-il-nal-TREX-one"

Uses

This medication is used to treat constipation caused by opioid medication. It blocks the effect of opioids on the gut without blocking the effect on pain. Methylnaltrexone belongs to a class of medications known as opioid antagonists.

How to Use This Medication

Read the Medication Guide provided by your pharmacist before you start taking methylnaltrexone and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth on an empty stomach as directed by your doctor, usually once daily at least 30 minutes before your first meal of the day.

The dosage is based on your medical condition and response to treatment.

Ask your doctor if you should keep using your usual medications for constipation. This medication is used only for constipation caused by opioids. Stop taking methylnaltrexone when you stop using opioid pain medication unless otherwise directed by your doctor.

Make sure you are close to a bathroom after taking this medication. This medication works quickly. Most people have a bowel movement within a few minutes to a few hours after taking this medication.

Tell your doctor if your condition lasts or gets worse.

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Information expires December 2025.