Oral Medications for Chronic Constipation
Start with polyethylene glycol (PEG) 17 g daily as first-line therapy for chronic idiopathic constipation, as it is the most effective, cost-efficient, and well-tolerated option with proven long-term safety. 1
First-Line Treatment: Osmotic Laxatives
Polyethylene Glycol (PEG) - Preferred Agent
- PEG 17 g daily is the gold standard first-line treatment for chronic constipation based on superior efficacy, safety profile, and cost-effectiveness 1
- Titrate dose based on symptom response and side effects with no clear maximum dose 1, 2
- Response is durable over 6-12 months of continuous use 1, 3, 4
- Monthly cost: $10-$45, making it significantly more affordable than prescription alternatives 1
- Common side effects include bloating, abdominal discomfort, and cramping 1
- Superior efficacy compared to tegaserod (50% vs 30.8% treatment success) 5
Alternative Osmotic Laxatives
- Magnesium oxide 400-500 mg daily: Use with caution in renal insufficiency and pregnancy 1
- Lactulose 15 g daily: Only osmotic agent studied in pregnancy, but bloating and flatulence may be limiting 1
Fiber Supplementation
- 14 g per 1,000 kcal intake daily 1
- Ensure adequate hydration as fiber intake increases 1
- Common side effects include bloating and abdominal discomfort 1
Second-Line Treatment: Stimulant Laxatives
Use when osmotic laxatives provide inadequate response:
- Bisacodyl 5 mg daily (maximum 10 mg daily): Recommended for short-term use or rescue therapy 1
- Senna 8.6-17.2 mg daily (maximum 4 tablets twice daily): Long-term safety and efficacy unknown 1
- Important caveat: Prolonged or excessive use can cause diarrhea and electrolyte imbalance 1
Prescription Secretagogues: For Refractory Cases
When first- and second-line therapies fail, consider prescription agents:
Lubiprostone
- 24 mcg twice daily for chronic idiopathic constipation 1, 6
- Chloride channel type 2 activator that increases intestinal secretion 1
- May provide additional benefit for abdominal pain 1
- Monthly cost: $374 1
- Diarrhea may occur in a subset of patients leading to discontinuation 1
Linaclotide
- Initial dose 72-145 mcg daily (maximum 290 mcg daily) 1, 7
- Guanylate cyclase-C agonist that increases intestinal secretion 1, 7
- May provide benefit for abdominal pain 1
- Monthly cost: $523 1
- Contraindicated in patients less than 2 years of age due to risk of severe dehydration 7
- Take on empty stomach at least 30 minutes before a meal 7
Plecanatide
- 3 mg daily (no titration needed) 1
- Guanylate cyclase-C agonist mechanism 1
- Monthly cost: $526 1
- Also approved for IBS-C 1
Prokinetic Agent: Alternative for Refractory Cases
Prucalopride
- 1-2 mg daily (maximum 2 mg daily) 1, 8
- Serotonin type 4 (5-HT4) receptor agonist that enhances colonic motility 1
- May provide additional benefit for abdominal pain 1
- Monthly cost: $563 1
- Headaches and diarrhea may occur in a subset of patients 1
- Recommended as second-line treatment in refractory CIC patients 8
Treatment Algorithm
- Start with PEG 17 g daily - most cost-effective with best evidence for long-term use 1, 3, 4
- If inadequate response after 2-3 days, titrate PEG dose upward based on clinical response 2
- If PEG alone fails, add or switch to stimulant laxatives (bisacodyl or senna) for short-term use 1
- For refractory cases, consider prescription secretagogues (lubiprostone, linaclotide, plecanatide) or prokinetic agent (prucalopride) 1, 8
- Ensure adequate hydration throughout treatment, especially with fiber and osmotic laxatives 1
Common Pitfalls to Avoid
- Do not use stimulant laxatives as first-line therapy - reserve for short-term use or rescue therapy due to unknown long-term safety 1
- Avoid magnesium-based laxatives in renal insufficiency - risk of hypermagnesemia 1
- Monitor for severe diarrhea with secretagogues - may require dose reduction or discontinuation 1, 7
- Do not crush or chew linaclotide capsules - administer whole or open capsule and mix with applesauce or water 7