What are the treatment options for a patient with chronic constipation?

Treatment of Chronic Constipation

Start with fiber supplementation (specifically psyllium) combined with adequate hydration, then escalate to polyethylene glycol (PEG) 17g daily if insufficient response, followed by stimulant laxatives (bisacodyl or senna) for refractory cases. 1, 2

Initial Assessment and Medication Review

• Discontinue constipating medications when feasible before initiating treatment (strong recommendation) 1
• Perform a digital rectal examination assessing pelvic floor motion during simulated evacuation to identify defecatory disorders 1
• Obtain only a complete blood count in the absence of alarm features; metabolic testing (glucose, calcium, TSH) is not recommended unless other clinical features warrant it 1
• Perform colonoscopy only if alarm features present (blood in stools, anemia, weight loss) or age-appropriate screening not completed 1

First-Line Treatment: Fiber Supplementation

• Use psyllium as the preferred fiber supplement, as it has the strongest evidence for effectiveness among all fiber types 1, 2, 3
• Assess total dietary fiber intake before recommending supplementation to avoid inadequate treatment 1, 4, 3
• Target at least 20-25g of total daily fiber intake, starting with 14g per 1,000 kcal of daily intake 4, 5
• Increase fiber gradually over several weeks to minimize bloating, flatulence, and abdominal pain 1, 5
• Ensure adequate hydration with fiber use—this is mandatory to prevent worsening constipation 1, 2, 4, 3

Second-Line Treatment: Osmotic Laxatives

• Escalate to polyethylene glycol (PEG) 17g daily when fiber supplementation provides insufficient relief (strong recommendation, moderate-quality evidence) 1, 2, 4, 3
• PEG demonstrates durable response over 6 months of continuous use 1, 4, 3
• Common side effects include abdominal distension, loose stools, flatulence, and nausea 1, 3
• Alternative osmotic agents include milk of magnesia (1 oz twice daily) or magnesium oxide (400-500mg daily, starting low and titrating up) 1, 4, 3
• Avoid magnesium-based laxatives in patients with renal insufficiency due to risk of hypermagnesemia 3, 6
• Lactulose (15g daily) is reserved for patients who fail or cannot tolerate over-the-counter therapies 4, 3

Third-Line Treatment: Stimulant Laxatives

• Add bisacodyl or glycerol suppositories (preferably 30 minutes after meals to synergize with gastrocolonic response) when osmotic laxatives are insufficient 1
• Bisacodyl or sodium picosulfate is strongly recommended for short-term use (≤4 weeks) or as rescue therapy 3
• Senna can be used but has lower quality evidence (conditional recommendation) 3
• Target one non-forced bowel movement every 1-2 days 1, 4
• All these agents cost approximately $1 or less per day 1

Fourth-Line Treatment: Prescription Secretagogues and Prokinetics

• Consider newer prescription agents when symptoms do not respond to laxatives 1
• Linaclotide 145 mcg once daily is FDA-approved for chronic idiopathic constipation in adults, demonstrating approximately 1.5 additional CSBMs per week compared to placebo 7
• Linaclotide improves stool frequency, consistency, and straining while reducing abdominal symptoms 7
• Lubiprostone (prostaglandin analog activating chloride channels) is effective for chronic constipation 1
• Both agents cost $7-9 per day (at time of 2013 guideline development) 1
• Prucalopride (5HT4 receptor agonist) is available outside the United States and has prokinetic properties 1

Special Population: Opioid-Induced Constipation

• Use peripherally acting μ-opioid receptor antagonists (methylnaltrexone 0.15 mg/kg every other day, maximum once daily, or naloxegol) when standard laxative therapy fails 1, 2
• These agents relieve opioid-induced constipation while preserving central analgesic effects 1
• Do not use methylnaltrexone in patients with postoperative ileus or mechanical bowel obstruction 1, 2
• Methylnaltrexone should be used as an adjunct to existing laxative therapy, not as monotherapy 1

Defecatory Disorders

• Refer for biofeedback therapy if anorectal testing reveals dyssynergic defecation—this improves symptoms in more than 70% of patients 1
• Evaluate colonic transit if anorectal test results do not show defecatory disorder or if symptoms persist despite treatment 1

Management of Fecal Impaction

• Treat fecal impaction with mineral oil or warm water enemas before initiating maintenance therapy 6
• Glycerol suppositories or phosphate enemas may be effective for acute management 1
• Manual disimpaction under anesthesia may be necessary for severe impaction 1

Critical Pitfalls to Avoid

• Failing to assess total dietary fiber intake before recommending supplementation leads to inadequate treatment 1, 2, 4, 3
• Not ensuring adequate hydration when increasing fiber can paradoxically worsen constipation 1, 2, 4, 3
• Using magnesium-based laxatives long-term or in patients with renal insufficiency risks toxicity 3, 6
• Performing extensive metabolic testing or colonoscopy without alarm features wastes resources and delays effective treatment 1