The purpose of a study published in BMC Gastroenterology was to assess the relative effectiveness of polyethylene glycol with (PEG + E) or without electrolytes (PEG) in the management of functional constipation in adults. This study entailed a systematic review to identify randomized controlled clinical trials that assessed the use of polyethylene glycol in functional constipation, where the primary outcome was mean number of bowel movements per week. Overall, 19 studies were selected involving 2,247 patients. The results showed that both, PEG and PEG + E were effective in treating functional constipation in adults. PEG could increase the number of bowel movements per week by 1.8 while PEG + E could increase it by 1.9 relative to placebo. On the other hand when compared to lactulose, these agents could confer increments in bowel movements by 1.8 and 1.9, respectively. Meanwhile, the efficacies, safety, and tolerability of PEG + E and PEG were found to be equivalent. Hence, it was inferred that polyethylene glycol with and without electrolytes is effective and safe for treating constipation in adults.