Substance guides

Opioid-induced constipation: Causes, treatment, and prevention

Published June 8, 2025 · 6 min read · Updated April 2026

Reviewed for accuracy by licensed clinical professionals.

Opioid-induced constipation (OIC) affects 40-80% of patients taking opioids and is one of the most common reasons people discontinue pain medication or MAT.

Why it happens

Opioids bind to mu receptors in the gut, slowing motility, increasing water absorption, and reducing secretions. Unlike most opioid effects, tolerance to constipation develops slowly or not at all.

Treatment

First-line: increase fiber, fluids, and physical activity. Osmotic laxatives (MiraLAX/polyethylene glycol). Stimulant laxatives (senna, bisacodyl). Prescription options: methylnaltrexone (Relistor) blocks opioid receptors in the gut without affecting pain relief or MAT. Naloxegol (Movantik) works similarly.

For MAT patients

Constipation is very common on methadone and Suboxone. Do not suffer in silence, as solutions exist. Start a bowel regimen when starting MAT rather than waiting for constipation to develop.

Authoritative sources

This article references guidelines from: NIDA · SAMHSA · CDC

Frequently asked questions

Does constipation from opioids go away?

Unlike most opioid effects, constipation tolerance develops very slowly or not at all. Active management is usually needed for as long as you take opioids.

What is the best laxative for opioid constipation?

MiraLAX (polyethylene glycol) is first-line. For refractory cases, methylnaltrexone (Relistor) specifically targets opioid-induced constipation.

Is constipation from Suboxone common?

Yes. It is one of the most common Suboxone side effects. Starting a bowel regimen when beginning MAT is recommended.

Disclaimer: Informational only. Not medical advice. SAMHSA: 1-800-662-4357.