Polyethylene Glycol Dosing for Constipation
For adults with chronic constipation, use PEG 3350 at 17 grams once daily mixed in 4-8 ounces of liquid; for children, start with 0.4 g/kg/day for maintenance therapy, and use 1-1.5 g/kg/day for fecal disimpaction over 3 days.
Adult Dosing
Standard Maintenance Dose
- Administer 17 grams of PEG 3350 once daily mixed in 4-8 ounces of any beverage (cold, hot, or room temperature) 1, 2
- This is the FDA-approved dose for occasional constipation, but has demonstrated efficacy for chronic idiopathic constipation (CIC) for up to 6 months 1
- Ensure the powder is fully dissolved before drinking; do not consume if clumps remain 2
Efficacy and Duration
- Treatment response is durable over 6 months with sustained efficacy 1
- PEG 3350 increases complete spontaneous bowel movements (CSBMs) by approximately 2.9 per week compared to placebo 1
- 42% of patients meet FDA responder criteria (≥3 CSBMs/week with ≥1 increase from baseline for ≥9/12 weeks) versus 13% with placebo 3
Treatment Algorithm for Adults
- Consider fiber supplementation first for mild constipation in patients with fiber-deficient diets 1
- Use PEG 3350 as first-line pharmacologic therapy either after fiber trial or in combination with fiber 1
- PEG can be used earlier in the treatment algorithm given its safety profile, low cost, and over-the-counter availability 1
Pediatric Dosing
Maintenance Therapy (Functional Constipation)
- Start with 0.4 g/kg/day of PEG 3350 for children with functional constipation 4
- This dose demonstrated 74% treatment success (≥3 bowel movements in the second week) versus 42% with placebo 4
- Doses of 0.2 g/kg/day showed similar efficacy (77% success), while 0.8 g/kg/day caused more abdominal pain and fecal incontinence 4
Disimpaction Therapy
- Use 1-1.5 g/kg/day for 3 days to treat fecal impaction in children 5
- Higher doses (1 and 1.5 g/kg/day) achieve 95% disimpaction success versus 55% with lower doses (0.25-0.5 g/kg/day) 5
- Home-based disimpaction over 3-6 days is as effective as hospital-based continuous lavage (94.7% vs 100% success) with fewer side effects and lower cost 6
Age-Specific Considerations
- For children under 24 months: Evidence is limited, but doses of 0.45-1.1 g/kg/day for PEG 3350 have been used safely 7
- For children 16 years and under: FDA labeling recommends consulting a physician, though clinical trials support use in this age group 2, 4
- For children 17 years and older: Use adult dosing of 17 grams once daily 2
Practical Measurement Guidance
Standard Measurements
- One capful (provided with bottle) = 17 grams 2
- One leveled tablespoon ≈ 10 grams 8
- One leveled teaspoon ≈ 3.3 grams 8
- Use leveled measurements with a dedicated measuring device to improve consistency and reduce dose variability 8
Safety Profile and Side Effects
Common Adverse Effects
- Bloating, flatulence, diarrhea, abdominal distension, loose stools, and nausea are expected laxative effects 1
- Most adverse events are mild to moderate 1
- Gastrointestinal adverse events decrease markedly after the first week of treatment 3
- Diarrhea occurs in approximately 158 more patients per 1,000 treated with PEG versus placebo 1
Safety Monitoring
- No clinically significant electrolyte changes have been documented 5
- Serious adverse events are rare, with no conclusive evidence of increased risk (RR 0.47, CI 0.16-1.33) 1
- No deaths or treatment discontinuations due to adverse events were reported in major trials 9
Important Caveats
Duration of Use
- FDA approval is for occasional constipation (up to 7 days without physician consultation) 2
- However, clinical evidence supports safe and effective use for up to 6 months in chronic constipation 1
- Do not use for more than 7 days without medical supervision per FDA labeling 2
Formulation Differences
- PEG 3350 without electrolytes (most common OTC formulation) is given once daily 1
- PEG 3350 with electrolytes has been studied at 17.5 grams twice daily 1
- Both formulations demonstrate similar efficacy profiles 1