See Chronic Constipation in Adults.
“For functional constipation in older adults, behavioral changes should be first-line management. These include scheduled toileting with proper positioning, increased intake of fiber and fluids, and avoiding bedpan use. If there is not an adequate response to behavioral interventions, osmotic laxatives should be initiated. Polyethylene glycol is more effective and has fewer side effects compared to lactulose. Magnesium salts, including magnesium citrate, do not have strong evidence for safety or efficacy, and magnesium toxicity is a concern with long-term use. Due to possible adverse effects of stimulant laxatives in the long term, particularly with older adults, these drugs should be used only if fiber and osmotic laxatives are unsuccessful.” ABFM Critique
Further Reading
Gastroenterology 2013;144(1):218-238. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3531555/
Management of constipation in older adults. Am Fam Physician 2015;92(6):500-504.