What are the recommendations for managing constipation?

Management of Constipation

Start with polyethylene glycol (PEG) 17g daily as first-line pharmacological therapy, combined with lifestyle modifications including fiber supplementation (14g/1,000 kcal intake) and adequate hydration. 1, 2

Initial Assessment and Non-Pharmacological Measures

Essential Evaluation Steps

• Perform digital rectal examination (DRE) to identify fecal impaction or full rectum, which changes management strategy 1
• Review all medications for constipating agents 1
• Assess for alarm features: severe symptoms, sudden bowel habit changes, blood in stool, or unexplained weight loss 1

Lifestyle Modifications (Implement Simultaneously)

• Fiber intake: Increase to 14g per 1,000 kcal daily intake, with psyllium being the most effective form 1, 2
• Hydration: Ensure adequate fluid intake, particularly when increasing fiber to prevent worsening symptoms 1, 2
• Positioning: Use footstool during defecation to elevate knees above hips, facilitating gravity-assisted evacuation 1, 2
• Toileting habits: Attempt defecation 30 minutes after meals (twice daily), strain no more than 5 minutes 1
• Physical activity: Increase within patient's functional limits 1

Critical caveat: Fiber supplementation alone has only conditional recommendation with low certainty evidence, and causes bloating/flatulence in many patients 1. Gradual titration over several days minimizes side effects 3.

First-Line Pharmacological Treatment

Osmotic Laxatives (Preferred Initial Agents)

• Polyethylene glycol (PEG): 17g daily, most cost-effective at $10-45/month with durable 6-month response 1, 2
• Lactulose: 15g daily if PEG unavailable; only osmotic agent studied in pregnancy but causes more bloating 1
• Magnesium oxide: 400-500mg daily, but contraindicated in renal insufficiency due to hypermagnesemia risk 1

The 2023 AGA-ACG guidelines provide strong support for osmotic laxatives as first-line therapy 1. PEG is preferred over lactulose due to better tolerability profile 1.

Stimulant Laxatives (Short-Term or Rescue Use)

• Bisacodyl: 5mg daily (maximum 10mg) 1
• Senna: 8.6-17.2mg daily 2
• Sodium picosulfate 1

Important limitation: Stimulant laxatives recommended primarily for short-term use or rescue therapy due to cramping, abdominal discomfort, and risk of electrolyte imbalance with prolonged use 1, 2.

Special Clinical Scenarios

Fecal Impaction Management

When DRE identifies fecal impaction, suppositories and enemas are first-line therapy, not oral laxatives 1:

• Digital fragmentation followed by water or oil retention enema 1
• Glycerin suppositories 2
• Once distal colon partially emptied, initiate oral PEG 1

Absolute contraindications to enemas: neutropenia (WBC <0.5 cells/μL), thrombocytopenia, intestinal obstruction, recent colorectal/gynecological surgery, severe colitis, undiagnosed abdominal pain, recent pelvic radiotherapy 1, 2

Opioid-Induced Constipation (OIC)

• Prophylactic laxative mandatory for all patients starting opioids unless pre-existing diarrhea 1
• Osmotic or stimulant laxatives preferred 1
• Bulk laxatives (psyllium) contraindicated in OIC 1
• For refractory OIC: peripheral opioid antagonists (methylnaltrexone, naloxegol) or combined opioid/naloxone formulations 1

Elderly Patients

• PEG 17g daily offers best safety profile 1
• Avoid liquid paraffin in bed-bound patients or those with swallowing disorders (aspiration pneumonia risk) 1
• Avoid bulk agents in non-ambulatory patients with low fluid intake (mechanical obstruction risk) 1
• Monitor closely if on diuretics or cardiac glycosides (dehydration/electrolyte imbalance risk) 1

Second-Line Prescription Therapies

When Over-the-Counter Agents Fail

Prucalopride is strongly recommended for refractory cases 2:

• Serotonin 5-HT4 receptor agonist promoting intestinal motility 1
• Treatment duration in trials: 4-24 weeks 2
• Common adverse effects: headache, abdominal pain, nausea, diarrhea 2

Alternative Prescription Options

• Linaclotide: 145mcg daily for chronic idiopathic constipation in adults; 72mcg for functional constipation in pediatric patients 6-17 years 4
  • Take on empty stomach 30 minutes before meals 4
  • Contraindicated in children <2 years (dehydration risk) 4
  • Contraindicated in mechanical GI obstruction 4

Common Pitfalls to Avoid

• Inadequate hydration with fiber: Worsens constipation rather than improving it 1, 2
• Long-term stimulant laxative use: Causes electrolyte imbalances and potential dependency 2
• Magnesium laxatives in renal disease: Risk of life-threatening hypermagnesemia 1, 2
• Bulk laxatives for OIC: Ineffective and potentially harmful 1
• Enemas in neutropenic patients: Risk of sepsis and perforation 1, 2

Treatment Algorithm Summary

1. Assess for fecal impaction via DRE → If present, use suppositories/enemas first 1
2. If no impaction: Start PEG 17g daily + fiber supplementation (14g/1,000 kcal) + lifestyle modifications 1, 2
3. If inadequate response: Add or switch to lactulose or magnesium oxide (if normal renal function) 1
4. For rescue therapy: Short-term bisacodyl or senna 1, 2
5. If refractory to OTC agents: Prescribe prucalopride or linaclotide 2, 4
6. Special populations: Prophylactic laxatives for opioid users; PEG preferred in elderly 1