The purpose of a study published in the Revista Espanola de Enfermedades was to evaluate the existing evidence on the use of polyethylene glycol (PEG), with or without electrolytes, in the management of functional constipation and the treatment of fecal impaction. In this study, a systematic search was conducted on MEDLINE, EMBASE and Cochrane databases until May 2016, for all publications on constipation and/or fecal impaction and PEG/polyethylene glycol. This descriptive analysis selected 58 publications, of which 41 were clinical trials, 8 were observational studies and 9 were systematic reviews or meta-analyses. The findings indicated that polyethylene glycol with or without electrolytes is more efficacious than placebo for the treatment of functional constipation in adults and in pediatric patients, with great safety and tolerability. These preparations constitute the most efficacious osmotic laxatives and are the first-line treatment for functional constipation, in the short and long-term. It was further stated that they are as efficacious as enemas in fecal impaction, avoid the need for hospital admission and exhibit excellent tolerance.