Management of Constipation

Initial Assessment and Treatment

The American Gastroenterological Association recommends starting with polyethylene glycol (PEG) 17g in 8 oz water once or twice daily as first-line pharmacologic therapy for adults with chronic idiopathic constipation, which has moderate-quality evidence showing durable response over 6 months 1
Before initiating treatment, it is essential to rule out bowel obstruction and fecal impaction through digital rectal examination (DRE) and abdominal examination, and obtain medication history to identify constipating agents that can be discontinued, according to the Annals of Oncology 2
The initial assessment should also include checking for alarm symptoms such as rectal bleeding, unintentional weight loss, and sudden change in bowel habits, as recommended by the Annals of Oncology 2

For patients with mild symptoms or dietary fiber deficiency, increasing fluid intake to at least 2 liters daily and trialing fiber supplementation with Psyllium are recommended, according to Gastroenterology 1
The American Gastroenterological Association suggests that polyethylene glycol (PEG) is the recommended first-line agent, with a dose of 17g (one capful) dissolved in 8 oz water once or twice daily, which has moderate-quality evidence showing durable response over 6 months 1
For severe refractory cases, metoclopramide 10-20 mg PO 3-4 times daily may be considered, as recommended by the Journal of the National Comprehensive Cancer Network 6

Prophylaxis is essential for opioid-induced constipation, and starting prophylactic laxatives with the first opioid dose is recommended, according to Praxis Medical Insights 3
The Journal of the National Comprehensive Cancer Network recommends a prevention strategy that includes starting stimulant laxative + stool softener, such as senna/docusate 2 tablets every morning, and escalating laxative dose when increasing opioid dose 6
For laxative-refractory cases, peripherally acting μ-opioid receptor antagonists (PAMORAs) such as methylnaltrexone 0.15 mg/kg subcutaneously every other day may be considered, as recommended by the Journal of the National Comprehensive Cancer Network and Annals of Oncology 2, 6