PEG = polyethylene glycol.
*A systematic review across PubMed and Embase of randomized controlled trials (≥4-week duration) that evaluated OTC constipation preparations between 2004 and 2020. Studies meeting the following selection criteria were included: 1) randomized controlled trial (placebo or active comparator); 2) parallel or crossover design; 3) established definition of constipation (preferably ROME criteria); 4) minimum duration of 4 weeks of active treatment; 5) well-defined clinical endpoints. Studies were scored using US Preventive Services Task Force criteria (0-5 scale) including randomization, blinding, and withdrawals. The strengths of evidence were adjudicated within each therapeutic category, and recommendations were graded (A, B, C, D, or I) based on level of evidence (Level I, good; Level II, fair; or III, poor).