Polyethylene glycol (PEG), particularly PEG 3350, is widely used and well-supported by scientific evidence for the treatment of constipation in adults. PEG is an osmotic laxative that works by retaining water in the stool, resulting in softer stools and increased bowel movements. Multiple high-quality randomized controlled trials (RCTs) and meta-analyses have demonstrated its efficacy and safety for treating both chronic and occasional constipation in adults.

Clinical guidelines from reputable organizations such as the American College of Gastroenterology, the American Gastroenterological Association, and the National Institute for Health and Care Excellence (NICE) recommend PEG as a first-line pharmacological therapy for chronic constipation. Studies consistently show that PEG improves stool frequency, stool consistency, and patient-reported symptoms compared to placebo and sometimes to other laxatives like lactulose. PEG is generally well-tolerated, with mild side effects such as bloating or flatulence being the most commonly reported.

The efficacy and safety profile of PEG has been established across diverse populations, including older adults and those with comorbidities. Its use is based entirely on rigorous scientific validation rather than traditional or anecdotal evidence.