Polyethylene Glycol (PEG): Medical Uses and Properties
Polyethylene glycol (PEG) is a long-chain polymer of ethylene oxide that acts as an osmotic laxative, widely available over-the-counter for the treatment of constipation. 1
Chemical Properties and Formulation
- PEG is available in formulations with and without electrolytes, typically as a powder to be dissolved in liquid 2
- The standard dose is 17g mixed in 8 ounces of liquid once daily 1, 2
- PEG is minimally absorbed from the gastrointestinal tract, making it safe for regular use 1
Mechanism of Action
- PEG functions as an osmotic laxative by drawing water into the intestinal lumen 1
- This increased water content softens stool and increases bowel movement frequency 1
- Unlike stimulant laxatives, PEG does not directly stimulate intestinal motility 1
Clinical Applications
- PEG is FDA-approved for the treatment of occasional constipation 1
- The American Gastroenterological Association (AGA) strongly recommends PEG for chronic idiopathic constipation (CIC) based on moderate certainty evidence 1
- For irritable bowel syndrome with constipation (IBS-C), the AGA suggests using PEG laxatives, though with a conditional recommendation based on low certainty evidence 1
- PEG is effective for pediatric constipation and is considered first-line therapy for children 3, 4
Efficacy
- PEG significantly increases complete spontaneous bowel movements (CSBMs) per week compared to placebo (mean difference 2.90, CI 2.12-3.68) 1
- It also increases spontaneous bowel movements (SBMs) per week (mean difference 2.30, CI 1.55-3.06) 1
- PEG demonstrates higher responder rates compared to placebo (RR 3.13, CI 2.00-4.89) 1
- Studies show PEG is superior to lactulose in outcomes of stool frequency, stool form, and relief of abdominal pain 5
Safety Profile
- PEG has a favorable safety profile with minimal systemic absorption 1
- Common side effects include abdominal distension, loose stool, flatulence, and nausea 1
- Serious adverse events are rare, with no significant difference compared to placebo 1
- Contraindicated in patients with known allergy to polyethylene glycol 2
Treatment Recommendations
- PEG can be used as first-line therapy after or in combination with fiber supplementation 1
- The AGA recommends starting with 17g of PEG daily for constipation 1, 6
- Response to PEG has been shown to be durable for up to 6 months 1
- For persistent constipation, PEG can be combined with other agents such as stimulant laxatives 6
Special Considerations
- PEG without electrolytes can be mixed with various beverages (juice, coffee, tea) for improved palatability 7
- PEG is available without prescription and is relatively inexpensive, making it accessible for most patients 1
- While effective for constipation symptoms, PEG has not shown significant improvement in abdominal pain for IBS-C patients 1
- Adequate hydration should be maintained when using PEG to optimize its efficacy 6