A study published in Revista Espanola de Enfermedades Digestivas evaluated the evidence published on the use of polyethylene glycol (PEG), with or without electrolytes, in the management of functional constipation and the treatment of fecal impaction. Investigators searched MEDLINE, EMBASE and Cochrane databases until May 2016. Fifty-eight publications were included in the descriptive analysis. Of these, 41 were clinical trials, eight were observational studies and nine were systematic reviews or meta-analysis. Twelve clinical trials evaluated PEG efficacy versus placebo, eight versus lactulose, six were dose studies, five compared PEG with and without electrolytes, two compared its efficacy with respect to milk of magnesia, and the rest of the trials evaluated PEG with enemas (two), psyllium (one), tegaserod (one), prucalopride (one), paraffin oil (one), fiber combinations (one) and Descurainia sophia (one). PEG, with or without electrolytes, was found to be more efficacious than placebo for the treatment of functional constipation, either in adults or in pediatric patients, with great safety and tolerability. These preparations constitute the most efficacious osmotic laxatives (more than lactulose) and are the first-line treatment for functional constipation in the short- as well as the long-term. They are as efficacious as enemas in fecal impaction, avoid the need for hospital admission and are well tolerated by patients.