Polyethylene Glycol 3350 Dosing and Administration

Dosing for Constipation

The American Gastroenterological Association recommends PEG 3350 at a dose of 17 g once daily mixed in 8 ounces of liquid for chronic constipation, with demonstrated efficacy for up to 6 months of continuous use 1
PEG 3350 is FDA-approved at a dose of 17 g daily for the treatment of occasional constipation and is widely available over-the-counter 2
For chronic idiopathic constipation (CIC), PEG has demonstrated significantly better efficacy than placebo in increasing complete spontaneous bowel movements (CSBMs) and spontaneous bowel movements (SBMs) 3
Response to PEG has been shown to be durable over 6 months of continuous use 2

For colonoscopy preparation, a split-dose regimen of 2 L PEG (half the evening before and half the morning of the procedure) is recommended 4, 5
For same-day colonoscopy procedures, a same-day regimen of 2-4 L PEG on the day of colonoscopy is an acceptable alternative 4, 5
For split-dose regimens, the second portion should begin 4-6 hours before colonoscopy and be completed at least 2 hours before the procedure (strong recommendation, moderate-quality evidence) 5
For morning colonoscopies, split-dose regimens are generally preferred over same-day dosing for optimal bowel preparation quality 5

Common side effects of PEG 3350 include abdominal distension, loose stool, flatulence, and nausea 2
Diarrhea is more common with PEG than placebo (158 more per 1,000 patients) 1

A trial of fiber supplement can be considered for mild constipation before PEG use or in combination with PEG 2
For chronic constipation, PEG can be used for extended periods (up to 6 months) with sustained efficacy 3
When using PEG for bowel preparation, the timing between the last dose and colonoscopy is critical - every additional hour between purgative completion and colonoscopy decreases preparation quality by approximately 10% 5
For optimal results, PEG should be taken with adequate fluid (8 ounces per dose) 2