What is the mechanism of action of macrogol (Polyethylene Glycol) 10g as a laxative?

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From the Guidelines

Macrogol (10g) laxative works primarily as an osmotic laxative to relieve constipation by drawing water into the intestinal lumen through osmosis, increasing the water content of stool and making it softer and easier to pass. When taken orally, macrogol (also known as polyethylene glycol or PEG) sequesters fluid in the bowel, as stated in the study by Nightingale JMD, et al. 1. The 10g dose is a standard therapeutic amount that effectively hydrates the stool without causing significant fluid and electrolyte imbalances. Unlike stimulant laxatives, macrogol doesn't irritate the intestinal wall or cause dependency with long-term use. It typically produces a bowel movement within 24-72 hours of administration. For optimal results, macrogol should be dissolved completely in water (usually 125-250ml) before consumption, and adequate fluid intake should be maintained throughout treatment. The medication works locally in the gut with minimal systemic absorption, making it safe for most patients including the elderly, pregnant women (under medical supervision), and those with various medical conditions. Some key points to consider when using macrogol (10g) laxative include:

  • The mechanism of action is osmotic, increasing water in the large bowel either by drawing fluid from the body into the bowel or by retaining the fluid that was administered 1
  • Macrogol is inert and does not cause significant fluid and electrolyte imbalances
  • It is safe for long-term use and does not cause dependency
  • Side effects are generally mild and may include abdominal bloating, flatulence, or nausea, particularly when treatment is initiated
  • The use of macrogol (10g) laxative is supported by guidelines from reputable organizations, such as the American Gastroenterological Association 1

From the Research

Mechanism of Macrogol Laxative

The mechanism of macrogol (10g) laxative can be understood as follows:

  • Macrogol is a biologically inert, non-absorbable osmotic laxative 2
  • It works by increasing the water content of the stool, making it softer and easier to pass 2, 3
  • Macrogol is not absorbed by the body and stays in the gut, where it helps to increase the frequency and consistency of stools 2, 4
  • The high-molecular-weight macrogols have a similar efficacy profile, but the taste of macrogol 4000 is generally preferred over that of macrogol 3350 + electrolytes 2

Comparison with Other Laxatives

  • Macrogol 4000 is more effective than lactulose in improving stool frequency and consistency, and is associated with less vomiting and flatulence 2
  • Macrogol 4000 is at least as effective as, or more effective than, psyllium hydrocolloid and magnesium hydroxide in treating chronic constipation 2
  • Current clinical treatment guidelines recommend the use of high-molecular-weight macrogols over the use of lactulose and bulk-forming laxatives in the symptomatic treatment of constipation in children and adults 2, 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Constipation in adults.

BMJ clinical evidence, 2010

Research

Evidence-based treatment recommendations for OTC management of chronic constipation.

Journal of the American Association of Nurse Practitioners, 2022

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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