Polyethylene Glycol (PEG) Dosage for Constipation
For adults with constipation, start with PEG 3350 17 grams once daily, dissolved in 4-8 ounces of any beverage, and titrate based on symptom response with no established maximum dose. 1, 2
Standard Dosing Regimen
- Initial dose: 17 grams (one capful or packet) once daily dissolved in 4-8 ounces of liquid (cold, hot, or room temperature) 2
- The dose can be titrated upward based on symptom response and tolerability, with no clear maximum dose established 1, 3
- The FDA label recommends not using for more than 7 days without physician consultation for over-the-counter use, though clinical guidelines support longer-term use 2
Evidence-Based Dosing Considerations
For chronic idiopathic constipation, the 2023 AGA-ACG guidelines provide a strong recommendation for PEG use with moderate-quality evidence 1:
- Response to PEG has been shown to be durable over 6 months of continuous treatment 1, 3
- Clinical trials demonstrate that 17 grams daily is effective for both short-term (1 week) and long-term (up to 12 months) treatment 4, 5, 6
- In a 24-week trial, 42% of patients met FDA responder criteria (≥3 complete spontaneous bowel movements per week with ≥1 increase from baseline) with 17 grams daily 4
Higher doses for acute relief: A single dose of 68 grams in 500 mL of flavored water provides safe and effective relief within 24 hours for acute constipation, with the second bowel movement occurring at a mean of 19.2 hours 7
Practical Administration Guidelines
- Ensure the powder is fully dissolved before drinking; do not consume if clumps remain 2
- Do not combine with starch-based thickeners used for dysphagia 2
- Adequate hydration should be encouraged during PEG use 3
- For children 16 years and under, consult a physician before use 2
Dose Titration Strategy
If constipation persists after initial dosing 1:
- The dose can be increased (e.g., to twice daily dosing) based on clinical response 1
- Consider adding other laxatives if PEG alone is insufficient, such as bisacodyl 10-15 mg daily to three times daily 1
- A trial of fiber supplement can be considered for mild constipation before PEG use or in combination with PEG 1
Side Effects and Safety
Common side effects include 1, 3, 5:
- Abdominal distension, bloating, and flatulence (may be dose-limiting, particularly if preexisting symptoms) 1
- Loose stools and nausea 1
- These effects are generally mild to moderate in severity 5
Long-term safety: Studies up to 12 months show no clinically significant changes in electrolytes, hematology, or blood chemistry, with no evidence of tachyphylaxis 5, 6
Clinical Context
- PEG is cost-effective at approximately $10-45 per month compared to prescription secretagogues ($523-563/month) 1, 3
- PEG is the only osmotic agent studied in pregnancy, making it a preferred option in this population 1
- For palliative care patients with life expectancy of months to weeks, PEG can be dosed as 1 capful in 8 ounces of water twice daily if constipation persists despite other interventions 1