What is the recommended starting dose of Polyethylene Glycol (PEG) for Irritable Bowel Syndrome with Constipation (IBS-C)?

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Last updated: October 6, 2025View editorial policy

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Recommended Dosage of PEG for IBS-C

The recommended starting dose of Polyethylene Glycol (PEG) for Irritable Bowel Syndrome with Constipation (IBS-C) is 17 g daily. 1

Dosing Guidelines for PEG in IBS-C

  • PEG 3350 is an osmotic laxative that works by drawing water into the intestine to increase stool bulk and facilitate passage 2
  • The standard initial dose of 17 g daily is recommended for patients with IBS-C 1
  • PEG can be titrated based on symptom response and side effects, with no clear maximum dose established 1
  • Response to PEG has been shown to be durable over 6 months of treatment 1

Efficacy of PEG for Constipation

  • Clinical studies have demonstrated that PEG is effective for the treatment of chronic constipation at the 17 g daily dose 3
  • In randomized controlled trials, PEG showed superior efficacy compared to placebo with 52% of patients achieving treatment success versus 11% with placebo 3
  • PEG has also demonstrated superior efficacy compared to tegaserod in the treatment of chronic constipation (50% vs 30.8% treatment success) 4

Administration and Monitoring

  • PEG should be dissolved in water or another beverage before consumption 2
  • Patients should be advised to maintain adequate hydration while using PEG 2
  • Dose adjustments can be made based on clinical response, typically after 2-3 days of treatment 1

Side Effects and Safety Considerations

  • Common side effects include bloating, abdominal discomfort, and cramping 1, 2
  • PEG is generally well-tolerated with a favorable safety profile even with long-term use 3
  • There is no significant risk of electrolyte imbalances at the recommended dose 5

Clinical Pearls

  • For patients requiring more rapid relief, higher initial doses (51-68 g) have been studied for short-term use, but the standard 17 g daily dose is appropriate for ongoing management 5
  • PEG is cost-effective compared to other prescription medications for IBS-C, with an estimated monthly cost of $10-$45 1
  • For patients with inadequate response to PEG alone, combination therapy with other agents may be considered, but should start with the standard PEG dose of 17 g daily 1

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Polyethylene Glycol Dosing Guidelines for Constipation

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Research

Overnight efficacy of polyethylene glycol laxative.

The American journal of gastroenterology, 2002

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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